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JavaScript

Ali .
Ali .
15,521 Points
Posted by Ali .
Ali .
15,521 Points

different between my code and course showing with "this"?

I just suggest. which one better?

// My code

const city = function(name, state){
  this.name = name;
  this.state = state;
  this.mycity = () => {
  console.log('My city is ' + this.name + ' ,and ' + this.state + ' is My state');
}};
city('Seattle', 'WA');
mycity()


/// course showing 

var city = function(name, state){
  this.name = name;
  this.state = state;
  this.mycity = function(){
  console.log('My city is ' + this.name + ' ,and ' + this.state + ' is My state');
}};

locations = new city('Seattle', 'WA');
locations.mycity();
// I hope to TTH to make a refresh courses for old courses.

1 Answer

Steven Parker
Steven Parker
229,732 Points
Steven Parker
Steven Parker
229,732 Points

The course example shows the creation of a function for constructing an object, and then using it with the "new" operator to make a new object instance. Then a method is called on the object. In that example, "this" represents the new object ("locations") that is constructed.

Your code is doing something different. By calling the function directly, no object is created but two global variables and a global function are created. And then you call the global function. In your code, "this" represents the global context instead of a new object.

Also, the MDN documentation for Arrow Functions says they "are best suited for non-method functions" and explains how they don't establish their own "this" like conventional functions do. If you used your function to create an object (using "new"), you could see this difference by calling the method from another context. The object method using the arrow function would completely ignore the new context:

locations.mycity.call({name: "Miami", state: "FL"});