How do I get the right “this” in an Array.map?

by

Just realized I should have read the documentation for Array.map() more carefully. One simply needs to pass in the this value as the second parameter of map()

http://codepen.io/anon/pen/VLggpX

a = {
  foo: 'bar',
  things: [1, 2, 3],
  showFooForEach: function() {
    this.things.map(function(thing) {
      console.log(this.foo, thing);
    }, this);
  }
}
a.showFooForEach();

In addition, understanding how bind(), call() and apply() work are a must for serious JavaScript developers. These allow us to skip silly assignments like

var self = this;
myItems.map(function(item) {
  self.itemArray.push(item);
});

with

myItems.map(function(item) {
  this.itemArray.push(item);
}.bind(this));

More Related Contents:

  1. Add/Remove Class of Nav Objects on Page Scroll
  2. XMLHttpRequest cannot load XXX No ‘Access-Control-Allow-Origin’ header
  3. Best way to detect when a user leaves a web page?
  4. How do I decode a string with escaped unicode?
  5. Javascript: Setting location.href versus location
  6. How to check whether a Storage item is set?
  7. Cache busting via params
  8. JSON.stringify doesn’t work with normal Javascript array
  9. Sort an array of object by a property (with custom order, not alphabetically)
  10. ‘this’ different between REPL and script
  11. How to check if an embedded SVG document is loaded in an html page?
  12. Why “this” is undefined inside a fat arrow function definition? [duplicate]
  13. What is the difference between JavaScript and ECMAScript?
  14. Make function wait until element exists
  15. anchor jumping by using javascript
  16. Have a div cling to top of screen if scrolled down past it [duplicate]
  17. Puppeteer log inside page.evaluate
  18. Resource interpreted as Document but transferred with MIME type application/zip
  19. Custom choices in JavaScript confirm dialog
  20. Regex remove repeated characters from a string by javascript
  21. Refresh page and run function after – JavaScript
  22. Querying by a field with type ‘reference’ in Firestore
  23. Is there a Sleep/Pause/Wait function in JavaScript? [duplicate]
  24. Why can’t React Hooks be called inside loops or nested function?
  25. How to trigger the onclick event of a marker on a Google Maps V3?
  26. Cannot connect to MongoDB because of wrong URI
  27. Low power mode detection in JavaScript for iOS11?
  28. How to implement a Typescript interface to an es5-style “class”?
  29. Explain bindbind() function
  30. read csv/tsv with no header line in D3

Leave a Comment