---
layout: page
title: "JavaScript method_exists function"
comments: true
sharing: true
footer: true
alias:
- /functions/view/method_exists:471
- /functions/view/method_exists
- /functions/view/471
- /functions/method_exists:471
- /functions/471
---
<!-- Generated by Rakefile:build -->
A JavaScript equivalent of PHP's method_exists

{% codeblock classobj/method_exists.js lang:js https://raw.github.com/kvz/phpjs/master/functions/classobj/method_exists.js raw on github %}
function method_exists (obj, method) {
  // http://kevin.vanzonneveld.net
  // +   original by: Brett Zamir (http://brett-zamir.me)
  // *     example 1: function class_a() {this.meth1 = function () {return true;}};
  // *     example 1: var instance_a = new class_a();
  // *     example 1: method_exists(instance_a, 'meth1');
  // *     returns 1: true
  // *     example 2: function class_a() {this.meth1 = function () {return true;}};
  // *     example 2: var instance_a = new class_a();
  // *     example 2: method_exists(instance_a, 'meth2');
  // *     returns 2: false
  if (typeof obj === 'string') {
    return this.window[obj] && typeof this.window[obj][method] === 'function';
  }

  return typeof obj[method] === 'function';
}
{% endcodeblock %}

 - [view on github](https://github.com/kvz/phpjs/blob/master/functions/classobj/method_exists.js)
 - [edit on github](https://github.com/kvz/phpjs/edit/master/functions/classobj/method_exists.js)

### Example 1
This code
{% codeblock lang:js example %}
function class_a() {this.meth1 = function () {return true;}};
var instance_a = new class_a();
method_exists(instance_a, 'meth1');
{% endcodeblock %}

Should return
{% codeblock lang:js returns %}
true
{% endcodeblock %}

### Example 2
This code
{% codeblock lang:js example %}
function class_a() {this.meth1 = function () {return true;}};
var instance_a = new class_a();
method_exists(instance_a, 'meth2');
{% endcodeblock %}

Should return
{% codeblock lang:js returns %}
false
{% endcodeblock %}


### Other PHP functions in the classobj extension
{% render_partial _includes/custom/classobj.html %}