The Headers.forEach()
method executes a callback function once per each key/value pair in the Headers
object.
The Headers.forEach()
method executes a callback function once per each key/value pair in the Headers
object.
js
forEach(callbackFn) forEach(callbackFn, thisArg)
callbackFn
Function to execute for each entry in the map. It takes the following arguments:
thisArg
Optional
Value to use as this
when executing callback
.
The Headers.forEach()
method executes the provided callback once for each key of the Headers which actually exist. It is not invoked for keys which have been deleted. However, it is executed for keys which are present but have the value undefined.
The following code logs a line for each key/value in the myHeaders
object.
js
// Create a new test Headers object const myHeaders = new Headers(); myHeaders.append("Content-Type", "application/json"); myHeaders.append("Cookie", "This is a demo cookie"); myHeaders.append("compression", "gzip"); // Display the key/value pairs myHeaders.forEach((value, key) => { console.log(`${key} ==> ${value}`); });
The result is:
compression ==> gzip content-type ==> application/json cookie ==> This is a demo cookie
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | |
forEach |
42 | 14 | 47 | No | 29 | 10.1 | 42 | 42 | 47 | 29 | 10.3 | 4.0 |
© 2005–2023 MDN contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/Headers/forEach