0
# Lodash IsString
1

2
Lodash IsString provides a standalone utility function for checking whether a value is classified as a String primitive or String object. This is the modern build of lodash's `_.isString` exported as a standalone Node.js module, enabling string type checking without importing the entire lodash library.
3

4
## Package Information
5

6
- **Package Name**: lodash.isstring
7
- **Package Type**: npm
8
- **Language**: JavaScript
9
- **Installation**: `npm install lodash.isstring`
10

11
## Core Imports
12

13
```javascript
14
const isString = require('lodash.isstring');
15
```
16

17
For ES modules:
18

19
```javascript
20
import isString from 'lodash.isstring';
21
```
22

23
For TypeScript:
24

25
```typescript
26
import isString from 'lodash.isstring';
27

28
// Type guard usage
29
function processValue(value: unknown): string | null {
30
  if (isString(value)) {
31
    // TypeScript now knows value is string
32
    return value.toUpperCase();
33
  }
34
  return null;
35
}
36
```
37

38
## Basic Usage
39

40
```javascript
41
const isString = require('lodash.isstring');
42

43
// Check string primitives
44
isString('hello');        // => true
45
isString('');            // => true
46

47
// Check String objects
48
isString(new String('hello')); // => true
49

50
// Check non-strings
51
isString(123);           // => false
52
isString(true);          // => false
53
isString(null);          // => false
54
isString(undefined);     // => false
55
isString([]);            // => false
56
isString({});            // => false
57
```
58

59
## Capabilities
60

61
### String Type Checking
62

63
Checks if a value is classified as a String primitive or String object. This function handles both JavaScript string primitives and String constructor objects correctly.
64

65
```javascript { .api }
66
/**
67
 * Checks if `value` is classified as a `String` primitive or object.
68
 * @param {*} value The value to check
69
 * @returns {boolean} Returns `true` if `value` is correctly classified, else `false`
70
 */
71
function isString(value);
72
```
73

74
**Implementation Details:**
75
- Uses `typeof value == 'string'` to detect string primitives
76
- Uses `Object.prototype.toString.call(value) == '[object String]'` to detect String objects
77
- Handles both primitive strings and String constructor instances
78
- Returns `false` for null, undefined, numbers, booleans, arrays, objects, and other non-string types
79

80
**Usage Examples:**
81

82
```javascript
83
const isString = require('lodash.isstring');
84

85
// String primitives
86
isString('abc');               // => true
87
isString('');                  // => true
88
isString('123');               // => true
89

90
// String objects
91
isString(new String('abc'));   // => true
92
isString(new String(''));      // => true
93

94
// Non-string values
95
isString(123);                 // => false
96
isString(true);                // => false
97
isString(false);               // => false
98
isString(null);                // => false
99
isString(undefined);           // => false
100
isString([]);                  // => false
101
isString({});                  // => false
102
isString(new Date());          // => false
103
isString(/regex/);             // => false
104
isString(function() {});       // => false
105

106
// Edge cases
107
isString(String(123));         // => true (converts to primitive string)
108
isString(Object('abc'));       // => true (creates String object)
109
```