Welcome to OStack Knowledge Sharing Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
1.6k views
in Technique[技术] by (71.8m points)

what is 'this' key word means in the javascript scenario?

I am new to javascript, I don't quite understand this.element = element; this.priority = priority; this means, is this means we have a element object. and this is point to the this element object, and this.element means element.elment? also what is this.enqueue = function(element, priority) this.enqueue means here? can someone gives me a heads up?

function PriorityQueue() {
  var items = [];

  function QueueElement(element, priority) {
    this.element = element;
    this.priority = priority;
  }
  this.enqueue = function(element, priority) {
    var queueElement = new QueueElement(element, priority);
    if (this.isEmpty()) {
      items.push(queueElement);
    } else {
      var added = false;
      for (var i = 0; i < items.length; i++) {
        if (queueElement.priority < items[i].priority) {
          items.splice(i, 0, queueElement);
          added = true;
          break;
        }
      }
      if (!added) {
        items.push(queueElement);
      }
    }
  };
question from:https://stackoverflow.com/questions/65848054/what-is-this-key-word-means-in-the-javascript-scenario

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Answer

0 votes
by (71.8m points)

From MDN docs

A function's this keyword behaves a little differently in JavaScript compared to other languages. It also has some differences between strict mode and non-strict mode.

In most cases, the value of this is determined by how a function is called (runtime binding). It can't be set by assignment during execution, and it may be different each time the function is called. ES5 introduced the bind() method to set the value of a function's this regardless of how it's called, and ES2015 introduced arrow functions which don't provide their own this binding (it retains the this value of the enclosing lexical context).

It's best if you read the documentation here


与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome to OStack Knowledge Sharing Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...