WeakMap

`WeakMap.prototype.get`

Returns the value associated with the specified key in the WeakMap, or undefined if the key is not present

Syntax

JavaScript

weakMap.get(key)

Parameters

Parameter	Type	Description
key	object	The key of the element to return

Return Value

The value associated with the key, or undefined

Examples

Basic Usage

const wm = new WeakMap()
const obj = { id: 1 }
wm.set(obj, 'data')
console.log(wm.get(obj)) // 'data'

Practical Example

const metadata = new WeakMap<HTMLElement, { clicks: number }>()
function trackClicks(el: HTMLElement) {
  const data = metadata.get(el) || { clicks: 0 }
  data.clicks++
  metadata.set(el, data)
  return data.clicks
}

Advanced Usage

const wm = new WeakMap<object, number>()
const a = {}
const b = {}
wm.set(a, 1)
console.log(wm.get(a)) // 1
console.log(wm.get(b)) // undefined

Understanding WeakMap.prototype.get

The WeakMap.prototype.get method in JavaScript returns the value associated with the specified key in the WeakMap, or undefined if the key is not present. It belongs to the WeakMap object and is one of the most widely used methods for working with weakmap values in modern JavaScript and TypeScript applications.

The method signature is weakMap.get(key). It accepts 1 parameter: key. When called, it returns the value associated with the key, or undefined. Understanding when and how to use get() helps you write more expressive, readable code.

Common use cases for WeakMap.prototype.get include data transformation, input validation, API response processing, and building reusable utility functions. It works well alongside related methods like weakmap-set, weakmap-has, weakmap-delete, enabling you to chain operations together for complex data manipulation pipelines.

Browser support for WeakMap.prototype.get is excellent across all modern browsers including Chrome, Firefox, Safari, and Edge. It is also fully supported in Node.js and Deno. For older environments, transpilation with Babel or a polyfill may be needed.