phpjs/functions/var/is_callable.js

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function is_callable(v, syntax_only, callable_name) {
  // From: http://phpjs.org/functions
  // +   original by: Brett Zamir (http://brett-zamir.me)
  // +      input by: François
  // +   improved by: Brett Zamir (http://brett-zamir.me)
  // %        note 1: The variable callable_name cannot work as a string variable passed by reference as in PHP (since JavaScript does not support passing strings by reference), but instead will take the name of a global variable and set that instead
  // %        note 2: When used on an object, depends on a constructor property being kept on the object prototype
  // *          test: skip
  // *     example 1: is_callable('is_callable');
  // *     returns 1: true
  // *     example 2: is_callable('bogusFunction', true);
  // *     returns 2: true // gives true because does not do strict checking
  // *     example 3: function SomeClass () {}
  // *     example 3: SomeClass.prototype.someMethod = function (){};
  // *     example 3: var testObj = new SomeClass();
  // *     example 3: is_callable([testObj, 'someMethod'], true, 'myVar');
  // *     example 3: $result = myVar;
  // *     returns 3: 'SomeClass::someMethod'
  // *     example 4: is_callable(function () {});
  // *     returns 4: true

  var name = '',
      obj = {},
      method = '';
  var getFuncName = function(fn) {
    var name = (/\W*function\s+([\w\$]+)\s*\(/).exec(fn);
    if (!name) {
      return '(Anonymous)';
    }
    return name[1];
  };
  if (typeof v === 'string') {
    obj = this.window;
    method = v;
    name = v;
  }
  else if (typeof v === 'function') {
    return true;
  }
  else if (Object.prototype.toString.call(v) === '[object Array]' &&
      v.length === 2 && typeof v[0] === 'object' && typeof v[1] === 'string') {
    obj = v[0];
    method = v[1];
    name = (obj.constructor && getFuncName(obj.constructor)) + '::' + method;
  }
  else {
    return false;
  }
  if (syntax_only || typeof obj[method] === 'function') {
    if (callable_name) {
      this.window[callable_name] = name;
    }
    return true;
  }
  return false;
}