this inside a function call gets set according to how a function is called. There are six main ways that this gets set. Normal Function Call: In a normal function call such as foo(), this is set to either the global object (which is window in a browser or global in nodejs) or to undefined … Read more
For preserving the context, the bind method is really useful, it’s now part of the recently released ECMAScript 5th Edition Specification, the implementation of this function is simple (only 8 lines long): // The .bind method from Prototype.js if (!Function.prototype.bind) { // check if native implementation available Function.prototype.bind = function(){ var fn = this, args … Read more
this.intervalID = setInterval(this.retrieve_rate.bind(this), this.INTERVAL);
It’s a reference to the current object, it’s most commonly used in object oriented code. Reference: http://www.php.net/manual/en/language.oop5.basic.php Primer: http://www.phpro.org/tutorials/Object-Oriented-Programming-with-PHP.html Example: <?php class Person { public $name; function __construct( $name ) { $this->name = $name; } }; $jack = new Person(‘Jack’); echo $jack->name; This stores the ‘Jack’ string as a property of the object created.
Use .bind() when you want that function to later be called with a certain context, useful in events. Use .call() or .apply() when you want to invoke the function immediately, and modify the context. Call/apply call the function immediately, whereas bind returns a function that, when later executed, will have the correct context set for … Read more
View.getContext(): Returns the context the view is currently running in. Usually the currently active Activity. Activity.getApplicationContext(): Returns the context for the entire application (the process all the Activities are running inside of). Use this instead of the current Activity context if you need a context tied to the lifecycle of the entire application, not just … Read more
ES6 React.Component doesn’t auto bind methods to itself. You need to bind them yourself in constructor. Like this: constructor (props){ super(props); this.state = { loopActive: false, shuffleActive: false, }; this.onToggleLoop = this.onToggleLoop.bind(this); }
I’m going to begin this answer with an illustration: var colours = [‘red’, ‘green’, ‘blue’]; document.getElementById(‘element’).addEventListener(‘click’, function() { // this is a reference to the element clicked on var that = this; colours.forEach(function() { // this is undefined // that is a reference to the element clicked on }); }); My answer originally demonstrated this … Read more
When do you use the “this” keyword? [closed]
EDIT: In summary, back in 2010 when this question was asked the most common way to solve this problem was to save a reference to the context where the setTimeout function call is made, because setTimeout executes the function with this pointing to the global object: var that = this; if (this.options.destroyOnHide) { setTimeout(function(){ that.tip.destroy() … Read more