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# Command Line Interface
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RequireJS r.js provides a comprehensive command line interface for building, optimizing, and running AMD-based JavaScript applications. The CLI supports multiple JavaScript environments including Node.js, Rhino, Nashorn, and xpcshell.
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## Basic Usage
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### Installation and Execution
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```bash
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# Install globally via npm
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npm install -g requirejs
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# Or use locally
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npm install requirejs
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# Run r.js directly (Node.js)
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node r.js [options] [script.js]
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# Use global installation
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r.js [options] [script.js]
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```
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### Command Structure
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```bash { .api }
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r.js [command-option] [arguments]
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```
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**Command Options:**
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- `-o` - Run optimizer/build
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- `-v` - Display version information
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- `-convert` - Convert CommonJS modules to AMD
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- `-lib` - Load bundled libraries
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## Core Commands
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### Running Scripts
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Execute AMD-based JavaScript applications:
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```bash { .api }
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# Run main application script
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r.js main.js
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# Run with specific module as entry point
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r.js app/startup.js
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# Run script in current directory (defaults to main.js if no file specified)
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r.js
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```
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### Version Information
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Display RequireJS version and environment details:
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```bash { .api }
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# Show version information
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r.js -v
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# Sample output:
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# r.js: 2.3.7, RequireJS: 2.3.7, Env: node, Command line args: -v
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```
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## Build and Optimization
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### Basic Build Command
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```bash { .api }
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# Build using configuration file
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r.js -o build.js
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# Build using configuration object
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r.js -o baseUrl=src name=main out=dist/main-built.js
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```
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### Build Configuration Options
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Pass build options directly via command line:
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```bash { .api }
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# Single module optimization
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r.js -o name=main baseUrl=js out=built/main.js
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# Multi-option build
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r.js -o appDir=src dir=dist baseUrl=. optimize=uglify
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# Specify configuration file
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r.js -o build/config.build.js
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# Multiple configuration sources
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r.js -o build.js baseUrl=override optimize=none
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```
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### Advanced Build Options
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```bash { .api }
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# CSS optimization
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r.js -o cssIn=css/main.css out=css/main-built.css optimizeCss=standard
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# Source map generation
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r.js -o build.js generateSourceMaps=true optimize=uglify2
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# Skip directory optimization  
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r.js -o build.js skipDirOptimize=true
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# Preserve license comments
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r.js -o build.js preserveLicenseComments=true
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```
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## Module Conversion
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### CommonJS to AMD Conversion
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Convert CommonJS modules to AMD format:
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```bash { .api }
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# Convert single directory
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r.js -convert path/to/commonjs/modules path/to/amd/modules
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# Convert with specific options
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r.js -convert src/commonjs dist/amd
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```
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**Conversion Process:**
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- Wraps CommonJS modules in AMD `define()` calls
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- Converts `require()` calls to dependency arrays
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- Handles `module.exports` and `exports` assignments
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- Maintains file structure and names
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### Conversion Examples
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```bash
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# Input CommonJS module (math.js):
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var helper = require('./helper');
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module.exports = {
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    add: function(a, b) { return a + b; }
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};
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# After conversion:
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define(['./helper'], function(helper) {
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    return {
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        add: function(a, b) { return a + b; }
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    };
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});
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```
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## Library Loading
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### Bundled Library Usage
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Load and use RequireJS with bundled libraries:
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```bash { .api }
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# Load with library support
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r.js -lib script.js
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# Available in script.js:
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# - requirejs/require/define functions
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# - Bundled utility libraries
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# - Environment abstraction
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```
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## Environment-Specific Usage
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### Node.js Environment
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```bash { .api }
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# Standard Node.js execution
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node r.js -o build.js
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# Use specific Node.js options
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node --max-old-space-size=4096 r.js -o large-build.js
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# Environment variable configuration
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NODE_ENV=production node r.js -o build.js
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```
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### Java/Rhino Environment
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```bash { .api }
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# Rhino execution with classpath
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java -classpath rhino.jar:. org.mozilla.javascript.tools.shell.Main r.js -o build.js
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# Nashorn execution (Java 8+)
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jjs r.js -- -o build.js
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# With Closure Compiler
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java -Xmx1g -classpath rhino.jar:closure-compiler.jar org.mozilla.javascript.tools.shell.Main r.js -o build.js optimize=closure
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```
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### xpcshell Environment (Mozilla)
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```bash { .api }
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# Firefox extension development
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xpcshell r.js -o addon-build.js
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# With Mozilla-specific options
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xpcshell -f r.js -e "load('build-script.js')"
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```
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## Configuration File Formats
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### JavaScript Configuration
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```javascript { .api }
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// build.js
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({
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    appDir: "src/",
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    baseUrl: "./",  
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    dir: "dist/",
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    modules: [
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        { name: "main" }
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    ],
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    optimize: "uglify"
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})
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```
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```bash
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r.js -o build.js
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```
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### JSON Configuration
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```json
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{
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    "appDir": "src/",
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    "baseUrl": "./",
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    "dir": "dist/",
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    "modules": [
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        { "name": "main" }
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    ],
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    "optimize": "uglify"
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}
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```
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```bash { .api }
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r.js -o build.json
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```
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### Command Line Configuration
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```bash { .api }
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# Inline configuration (single line)
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r.js -o "({appDir:'src',dir:'dist',modules:[{name:'main'}]})"
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# Mixed file and inline options
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r.js -o build.js optimize=none generateSourceMaps=true
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```
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## Output and Logging
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### Standard Output Control
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```bash { .api }
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# Write optimized output to stdout
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r.js -o build.js out=stdout
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# Combine with other tools
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r.js -o name=main baseUrl=src out=stdout | gzip > main.js.gz
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# Silent operation
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r.js -o build.js logLevel=4
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```
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### Log Levels
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```bash { .api }
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# Trace level (most verbose)
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r.js -o build.js logLevel=0
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# Info level (default)
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r.js -o build.js logLevel=1
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# Warning level
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r.js -o build.js logLevel=2
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# Error level
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r.js -o build.js logLevel=3
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# Silent (no output)
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r.js -o build.js logLevel=4
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```
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## Error Handling and Debugging
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### Common Error Scenarios
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```bash
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# Missing build file
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r.js -o nonexistent.js
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# Error: ENOENT: no such file or directory
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# Invalid configuration
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r.js -o "({invalid:syntax})"
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# Error: SyntaxError: Unexpected token
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# Module not found
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r.js -o name=missing baseUrl=src out=dist/missing.js
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# Error: Module name "missing" has not been loaded yet
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```
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### Debugging Options
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```bash { .api }
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# Verbose output with trace information
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r.js -o build.js logLevel=0
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# Preserve intermediate files for debugging
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r.js -o build.js keepBuildDir=true
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# Generate source maps for debugging minified code
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r.js -o build.js generateSourceMaps=true
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# Skip minification for debugging
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r.js -o build.js optimize=none
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```
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## Build Performance Options
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### Optimization Control
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```bash { .api }
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# Fast development builds
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r.js -o build.js optimize=none skipDirOptimize=true
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# Maximum optimization
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r.js -o build.js optimize=uglify generateSourceMaps=false removeCombined=true
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# Memory usage control (Node.js)
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node --max-old-space-size=8192 r.js -o large-build.js
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```
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### Incremental Builds
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```bash { .api }
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# Keep previous build directory for faster rebuilds
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r.js -o build.js keepBuildDir=true
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# Only rebuild changed modules
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r.js -o build.js skipDirOptimize=true
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```
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## Integration Examples
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### Build Scripts
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```bash
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#!/bin/bash
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# build.sh
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# Development build
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echo "Building development version..."
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r.js -o build-dev.js
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# Production build  
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echo "Building production version..."
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r.js -o build-prod.js
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# Create source maps
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echo "Generating source maps..."
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r.js -o build-prod.js generateSourceMaps=true
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```
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### Package.json Scripts
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```json
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{
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  "scripts": {
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    "build": "r.js -o build.js",
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    "build:dev": "r.js -o build-dev.js",
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    "build:prod": "r.js -o build-prod.js",
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    "watch": "nodemon --exec 'npm run build:dev' --watch src/",
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    "convert": "r.js -convert src/commonjs dist/amd"
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  }
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}
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```
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### Continuous Integration
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```bash
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# CI build script
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set -e  # Exit on any error
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echo "Converting CommonJS modules..."
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r.js -convert lib/commonjs lib/amd
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echo "Running build optimization..."  
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r.js -o build-ci.js
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echo "Build completed successfully"
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```
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## Help and Documentation
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### Getting Help
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```bash { .api }
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# Show help information
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r.js -help
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r.js --help
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r.js -h
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# Online documentation reference
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# See https://github.com/requirejs/r.js for usage.
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```
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### Command Line Reference
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The r.js command line tool provides a flexible interface for all RequireJS optimization and execution needs, supporting multiple JavaScript environments and extensive configuration options for modern web application builds.