JavaScript functions cannot be call one from another

Question

I get desired output from below code. These are two JavaScript function expressions for printing data

(function(){
var getData=function()
{
   console.log("getdata");
},
setData=function()
{
  getData();
  console.log("setData");
};
setData();
})();

But when I try something like this in another page.I didn't get desired output.

This is my code.

var employeesList = {
    getemployees: function () {
    var data= getData("Employees/GetEmployees");
    },
    init: function () {
        this.getemployees();
    }
}.init();

  var getData = function (url) {
    var error = false;

    $.ajax({
        type: 'GET',
        url: url,
        dataType: 'json',
        success: function (data) {
            return data;
        },
        error: function () {
            return error = true;
        }

    });
};

I got an error like this. getData is not a function please help.

move var getData = function (url) { above var employeesList = { — Arun P Johny
– Arun P Johny, Commented Apr 26, 2017 at 6:43
Or declare it like function functionName() {} instead of using a variable. That way it'll be usable before being declared. — Hissvard
– Hissvard, Commented Apr 26, 2017 at 6:45
Now it is working.i forget the concept JavaScript Hoisting. Thanks for remembering me. — John. Developer
– John. Developer, Commented Apr 26, 2017 at 6:45
function functionName() {} this is function declaration. This will initialize on initial function call. — John. Developer
– John. Developer, Commented Apr 26, 2017 at 6:49

Alessandro · Accepted Answer · 2017-04-26 06:52:27Z

1

You can't use a variable before have defined it, so you have to declare getData before employeesList
The variable data in getemployees couldn't be accessible, I added a return there, so you can use its value in init

var getData = function (url) {
    var error = false;

    /*$.ajax({
        type: 'GET',
        url: url,
        dataType: 'json',
        success: function (data) {
            return data;
        },
        error: function () {
            return error = true;
        }

    });*/
    return 'test_result';
};

var employeesList = {
    getemployees: function () {
        //Here you should return the result
        return getData("Employees/GetEmployees");
    },
    init: function () {
        var res = this.getemployees();
        console.log(res);
    }
}.init();

I hope it was clear, bye.

answered Apr 26, 2017 at 6:52

Alessandro

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zoly01 · Accepted Answer · 2017-04-26 06:58:51Z

0

There are two methods to define "function":

var func_name = function(){...}
function func_name() {...}

The difference is that when you use the second one, it can be called before being declared.

var employeesList = {
    getemployees: function () {
    var data= getData("Employees/GetEmployees");
    },
    init: function () {
        this.getemployees();
    }
}.init();

  //var getData = function (url) {
function getData (url) { // <====== change to this
    var error = false;

    $.ajax({
        type: 'GET',
        url: url,
        dataType: 'json',
        success: function (data) {
            return data;
        },
        error: function () {
            return error = true;
        }

    });
};

edited Apr 26, 2017 at 6:58

answered Apr 26, 2017 at 6:52

zoly01

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