JavaScript handler.apply() method in JavaScript is used as a trap for a function call. The value returned by this method is used as the result of a function call through a proxy.
Syntax:
const p = new Proxy(target, {
apply: function(target, thisArg, argumentsList) {
}
});
Parameters: This method accepts three parameters as mentioned above and described below:
- target: This parameter holds the target object.
- thisArg: This parameter is used for the call.
- argumentsList: This parameter contains the list as the argument and is used for the call.
Return value: This method returns any value.
Below examples illustrate the handler.apply() method in JavaScript:
Example 1: In this example, we will calculate the sum of the numbers using the handler.apply() method in JavaScript.
javascript
function sum(a, b) { return a + b;}const handler = { apply: function (target, thisArg, argumentsList) { console.log(`Calculate sum: ${argumentsList}`); return target(argumentsList[0], argumentsList[1]) * 14 / 3; }};const proxy1 = new Proxy(sum, handler);console.log(sum(23, 4));console.log(proxy1(23, 4)); |
Output:
27 "Calculate sum: 23, 4" 126
Example 2: In this example, we will print values using the handler.apply() method in JavaScript.
javascript
let str = function (arg1, arg2) { console.log('neveropen get (' + arg1 + ', ' + arg2 + ')');};let proxy = new Proxy(str, { apply: function (target, thisArg, parameters) { console.log('Geeksforneveropen'); return target.apply(thisArg, parameters); }});proxy('Tutorial', 'Jobs');proxy.apply(null, ['Knowledge', 'internships']);proxy.call(null, 'Stipend', 'skills'); |
Output:
"Geeksforneveropen" "neveropen get (Tutorial, Jobs)" "Geeksforneveropen" "neveropen get (Knowledge, internships)" "Geeksforneveropen" "neveropen get (Stipend, skills)"
Supported Browsers: The browsers supported by JavaScript handler.apply() method are listed below:
- Google Chrome 49 and above
- Edge 12 and above
- Firefox 18 and above
- Opera 36 and above
- Safari 10 and above
We have a complete list of Javascript Proxy/handler methods, to check those go through the Javascript Proxy/handler Reference article.
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