append method Null safety

Object append(
  1. String name,
  2. String value

Appends a new value onto an existing header inside a Headers object, or adds the header if it does not already exist. myHeaders.append(name, value); Creating an empty Headers object is simple:

var myHeaders = new Headers(); // Currently empty

You could add a header to this using append():

myHeaders.append('Content-Type', 'image/jpeg'); myHeaders.get('Content-Type'); // Returns 'image/jpeg' If the specified header already exists, append() will change its value to the specified value. If the specified header already exists and accepts multiple values, append() will append the new value to the end of the value set:

myHeaders.append('Accept-Encoding', 'deflate'); myHeaders.append('Accept-Encoding', 'gzip'); myHeaders.get('Accept-Encoding'); // Returns 'deflate, gzip'

To overwrite the old value with a new one, use Headers.set.


external Object append(String name, String value);