this value in JavaScript anonymous function

by

Inside of your anonymous function this is the global object.

Inside of test, this is the instance of MyObject on which the method was invoked.

Whenever you call a function like this:

somceFunction(); // called function invocation

this is always the global object, or undefined in strict mode (unless someFunction was created with bind** — see below)

Whenever you call a function like this

foo.someMethod();  //called method invocation

this is set to foo

**EcmaScript5 defines a bind function that allows you to create a function that has a pre-set value for this

So this

    var obj = { a: 12 };
    var someFunction = (function () { alert(this.a); }).bind(obj);
    someFunction();

Causes someFucntion to be invoked with this equal to obj, and alerts 12. I bring this up only to note that this is a potential exception to the rule I mentioned about functions invoked as

someFunction();

always having this equal to the global object (or undefined in strict mode)

More Related Contents:

  1. What does “this” refer to in arrow functions in ES6?
  2. Anonymous class instance —- is it a bad idea?
  3. Arrow Functions and This [duplicate]
  4. Why do arrow functions not have the arguments array? [duplicate]
  5. “This” within es6 class method [duplicate]
  6. How to bind methods when destructuring an object in JavaScript?
  7. Call static methods from regular ES6 class methods
  8. Javascript “this” pointer within nested function
  9. ECMAScript 6 features available in Node.js 0.12
  10. ES6: Conditional & Dynamic Import Statements
  11. JS/ES6: Destructuring of undefined
  12. Can’t require() default export value in Babel 6.x
  13. How to know when all Promises are Resolved in a dynamic “iterable” parameter?
  14. ES6 classes : what about instrospection?
  15. ES6 Destructuring and Module imports
  16. forEach is not a function error with JavaScript array
  17. requestAnimationFrame with this keyword
  18. Why es6 react component works only with “export default”?
  19. How to publish a module written in ES6 to NPM?
  20. What is the defined execution order of ES6 imports?
  21. Lazy getter doesn’t work in classes
  22. Why does the Promise constructor require a function that calls ‘resolve’ when complete, but ‘then’ does not – it returns a value instead?
  23. Get the description of a ES6 Symbol
  24. How to create an array of objects from multiple arrays
  25. How should I import the Spatial Illusions milsymbol library into my webpage?
  26. Why is `throw` invalid in an ES6 arrow function?
  27. Where argument of first next() call goes? [duplicate]
  28. Unnecessary ‘else’ after ‘return’. (No-else-return)
  29. using await on global scope without async keyword
  30. ESLint: “error Parsing error: The keyword ‘const’ is reserved”

Leave a Comment