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lodash.ismap

The lodash.ismap package provides the _.isMap utility method as a standalone Node.js module. It checks if a value is a Map object using internal object type checking mechanisms, offering cross-environment compatibility and optimal performance.

Package Information

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

Core Imports

var isMap = require('lodash.ismap');

Basic Usage

var isMap = require('lodash.ismap');

// Check if value is a Map
isMap(new Map);
// => true

isMap(new WeakMap);
// => false

isMap({});
// => false

isMap([1, 2, 3]);
// => false

isMap(null);
// => false

Capabilities

Map Type Checking

Checks if a value is classified as a Map object with cross-environment compatibility.

/**
 * Checks if `value` is classified as a `Map` object.
 *
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is a map, else `false`.
 */
function isMap(value);

Parameters:

  • value (*): The value to check

Returns:

  • boolean: Returns true if value is a map, else false

Implementation Details:

The function uses two different strategies based on the environment:

  1. Node.js Environment: Uses native util.isMap for optimal performance when available
  2. Browser/General Environment: Falls back to object type checking using Object.prototype.toString

The implementation handles cross-browser compatibility issues and provides accurate Map detection across different JavaScript environments, including:

  • Native Map support in modern browsers
  • IE 11 compatibility issues
  • Node.js optimizations
  • Host object detection in older IE versions

Usage Examples:

var isMap = require('lodash.ismap');

// Standard Map object
var myMap = new Map([['key1', 'value1'], ['key2', 'value2']]);
console.log(isMap(myMap)); // => true

// WeakMap (not a Map)
var myWeakMap = new WeakMap();
console.log(isMap(myWeakMap)); // => false

// Plain objects
console.log(isMap({})); // => false
console.log(isMap({ a: 1 })); // => false

// Arrays
console.log(isMap([])); // => false
console.log(isMap([1, 2, 3])); // => false

// Primitives
console.log(isMap(null)); // => false
console.log(isMap(undefined)); // => false
console.log(isMap(42)); // => false
console.log(isMap('string')); // => false
console.log(isMap(true)); // => false

// Edge cases
console.log(isMap(new Set())); // => false
console.log(isMap(new Date())); // => false
console.log(isMap(/regex/)); // => false