looping over ajax call to exit when the variable is "No" in javascript

Question

I have been working for the last two days and struggling to find a solution. Would be helpful if someone helps me. I am using nodejs and Vue.

• How should i come out from the ajax call when I get "No" result and need to stop the loop.
• Not able to access the userExist array variable.
• Also the same for when i converted to this.info['isthisUser'] Vue variable.+

var thisUser = ["NY","NJ","CT","CA"]

var userExist = mycheck(thisUser)
console.log(userExist);

this.info['isthisUser'] = userExist;
console.log(this.info['isthisUser']);    

function mycheck(val) { 
    var usCNT = val.length; 
    var array = new Array();

    if (usCNT>0) {
        for (var u=0; u<usCNT; u++) {
        var checkThisUser = val[u];
            $.ajax
            ({
            type: "POST",
            url: '/getStates',
            data: { user: checkThisUser,},
            success: function (data, msg) {
            result = data ; 
            array.push(result);
            if(result === 'No') {
                alert('not exist');
                }
            })
        }
    }   
    return array;
};

console.log(userExist) shows this format

[]
0: "No"
1: "No"
2: "No"
3: "Yes"
length: 4
__ob__: Observer {value: Array(4), dep: Dep, vmCount: 0}
__proto__: Array

console.log(this.info['isthisUser']) shows the below

[__ob__: Observer]
0: "No"
1: "No"
2: "No"
3: "Yes"
length: 4
__ob__: Observer {value: Array(4), dep: Dep, vmCount: 0}
__proto__: Array

Answer 1

This code is obsolete, also $.ajax requests are performed in parallel, so exiting early from a loop won't prevent them from being completed, unless they are explicitly aborted.

In case requests should be performed sequentially, a straightforward way to do this is async..await. $.ajax is able to return a promise:

async function mycheck(val) { 
    ...
    var array = [];
    for (var u=0; u<usCNT; u++) {
        var result = await $.ajax({
          type: "POST",
          url: '/getStates',
          data: { user: checkThisUser,}
        });
        if (result === 'No') {
            throw new Error('not exist');
        }
        array.push(result);
    }
    return array;
};

The use of promises requires to consistently use them, either with async..await or plain then and catch. Since mycheck is able to return rejected promise on throw, an error should be handled in a caller.

If the intention of this function is to return a boolean, it can be simplified to:

    ...
    for (var u=0; u<usCNT; u++) {
        var result = await $.ajax({
          type: "POST",
          url: '/getStates',
          data: { user: checkThisUser,}
        });
        if (result === 'No') {
           return false;
        }
    }
    return true;