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tessl/npm-lodash-reinterpolate

Internal lodash utility providing a regular expression for template interpolation delimiters

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lodash._reinterpolate

lodash._reinterpolate is an internal lodash utility module that provides a regular expression for matching template interpolation delimiters. It exports a single RegExp constant used by lodash's template system to identify ERB-style interpolation expressions enclosed in <%= and %> tags.

Package Information

  • Package Name: lodash._reinterpolate
  • Package Type: npm
  • Language: JavaScript
  • Installation: npm install lodash._reinterpolate

Core Imports

var reInterpolate = require('lodash._reinterpolate');

For ES modules:

import reInterpolate from 'lodash._reinterpolate';

Basic Usage

var reInterpolate = require('lodash._reinterpolate');

// Use the regex to find template interpolation patterns
var template = 'Hello <%=name%>, you have <%=count%> messages.';
var matches = template.match(reInterpolate);

console.log(matches);
// Output: ['<%=name%>', '<%=count%>']

// Extract interpolation expressions
var expressions = [];
var match;
while ((match = reInterpolate.exec(template)) !== null) {
  expressions.push(match[1]); // Capture group contains the expression
}

console.log(expressions);
// Output: ['name', 'count']

Capabilities

Template Interpolation Pattern Matching

The module exports a single regular expression constant that matches ERB-style template interpolation delimiters.

/**
 * Regular expression for matching template interpolation delimiters.
 * Matches patterns like <%=expression%> and captures the expression content.
 * Pattern: /<%=([\s\S]+?)%>/g
 * - <%=      : Opening delimiter
 * - ([\s\S]+?) : Capture group for any characters including newlines (non-greedy)
 * - %>       : Closing delimiter  
 * - g        : Global flag for multiple matches
 */
var reInterpolate = /<%=([\s\S]+?)%>/g;

The regex pattern /<%=([\s\S]+?)%>/g specifically:

  • Matches the opening delimiter <%=
  • Captures any content including whitespace and newlines using [\s\S]+? (non-greedy)
  • Matches the closing delimiter %>
  • Uses the global flag g to find all matches in a string

Usage Examples:

var reInterpolate = require('lodash._reinterpolate');

// Simple interpolation matching
var simple = 'Welcome <%=user%>!';
console.log(simple.match(reInterpolate));
// Output: ['<%=user%>']

// Multiple interpolations
var multiple = 'Hello <%=firstName%> <%=lastName%>, you have <%=messageCount%> messages.';
var allMatches = multiple.match(reInterpolate);
console.log(allMatches);
// Output: ['<%=firstName%>', '<%=lastName%>', '<%=messageCount%>']

// Extract just the expressions using capture groups
var expressions = [];
var match;
// Reset regex lastIndex before using exec in a loop
reInterpolate.lastIndex = 0;
while ((match = reInterpolate.exec(multiple)) !== null) {
  expressions.push(match[1].trim());
}
console.log(expressions);
// Output: ['firstName', 'lastName', 'messageCount']

// Handle expressions with spaces and complex content
var complex = 'Result: <%=  user.name.toUpperCase()  %>';
var result = reInterpolate.exec(complex);
console.log(result[1]);
// Output: '  user.name.toUpperCase()  '
console.log(result[1].trim());
// Output: 'user.name.toUpperCase()'

// Multiline expressions (supported by [\s\S])
var multiline = `Template with <%=
  someFunction() +
  anotherValue
%> expression`;
reInterpolate.lastIndex = 0;
var multilineMatch = reInterpolate.exec(multiline);
console.log(multilineMatch[1]);
// Output includes the newlines and whitespace

Technical Details

This is a minimal utility module with zero dependencies, designed for maximum reusability. The regular expression is specifically crafted for lodash's internal template system but can be used independently for matching ERB-style interpolation patterns in any string.

Key characteristics:

  • Zero dependencies: Pure JavaScript with no external requirements
  • Global matching: Use the g flag to find all interpolation patterns in a string
  • Capture groups: The parentheses capture the expression content without delimiters
  • Whitespace handling: Captures all whitespace as-is; trimming must be done separately
  • Newline support: [\s\S] character class includes newlines for multiline expressions
  • Non-greedy matching: +? ensures minimal matching to avoid capturing multiple expressions as one

Common patterns:

  • Use string.match(reInterpolate) to get all matches as an array
  • Use reInterpolate.exec() in a loop to access capture groups
  • Always reset reInterpolate.lastIndex = 0 before using exec() in loops
  • Use match[1].trim() to get clean expression content without surrounding whitespace

docs

index.md

tile.json