web api instance method
Headers: forEach() method
Available in workers
The Headers.forEach() method executes a callback function once per each key/value pair in the Headers object.
Syntax
forEach(callbackFn)
forEach(callbackFn, thisArg)
Parameters
callbackFn- : Function to execute for each entry in the map. It takes the following arguments:
value- : Value of the currently visited header entry.
key- : Name of the currently visited header entry.
object- : The Headers object being iterated.
- : Function to execute for each entry in the map. It takes the following arguments:
thisArgOptional- : Value to use as
thiswhen executingcallback.
- : Value to use as
Return value
Description
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.
Examples
Printing the contents of Headers object
The following code logs a line for each key/value in the myHeaders object.
// 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
Specifications
SpecificationsStandards references are available on the canonical MDN page.
Browser compatibility
Browser compatibilityCompatibility data is available on the canonical MDN page.