在ajax调用之外访问数组？

Question

all! I have an ajax call grabbing the results of an API. When I try to access that array outside the call, it's blank. Help?

In the code below, I get the list of properties, then assign the results to the "mlsArray" variable. When I console log it inside main, I get the desired result.

However, if I later call getHomes, the array is empty.

main(auth) {
$.ajax({async: false,
    url: "https://api.simplyrets.com/properties? 
limit=500&lastId=0&status=active&maxprice=" +
    this.maximum + "&type=residential",
    type: 'GET',
    dataType: 'json',
    // authorize with the API credentials
    beforeSend: function(xhr) {
        xhr.setRequestHeader("Authorization", "Basic  " + auth);
    },
    success: function(res) {
     this.mlsArray  = Object.assign([], res);
     console.log(this.mlsArray);
    }
  });
}

 getHomes() {
  console.log(this.mlsArray);
 }
}

Answer 1

What you're dealing with here is javascript this "scoping" rules. The context of a function ( by default ) takes on the context of the object that invokes it ( see: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/this ).

When you're invoking the function success , you need to bind the context to the one you want inside the function:

success: function (res) {
 // do things ...
}.bind(this)

Good luck!

Answer 2

the this here refers to the ajax object .

this.mlsArray  = Object.assign([], res);

wherein the this here below refers to the window object which has all the global properties and methods.

getHomes() {
  console.log(this.mlsArray);
 }

1.Either bind the values to the window object by using

success: function (res) {
 this.mlsArray  = Object.assign([], res);
 console.log(this.mlsArray);
}.bind(this)

or

2. make mlsArray as a global variable and refrain from using this keyword.

   success: function (res) { mlsArray = Object.assign([], res); console.log(mlsArray); }

and in getHomes like below

getHomes() {
  console.log(mlsArray);
 }

Answer 3

您应该将ajax调用的success部分中的值分配给全局变量，以便即使在main()函数外部也可以访问它。