I want some jquery variables to be created dynamically. In my code I am having a loop, and with the loop values I want to create some variables. Here is my sample code.

array=["student","parent","employee"]

$.each(user_types, function( index, value ){
  var value+"_type" // this is the type of variable i want to build.
})

I have found about eval function. That code goes like this.

var type = "type"
eval("var pre_"+type+"= 'The value of dynamic variable, val';");

alert(pre_type) // this gives 'The value of dynamic variable, val' in alert box.

Is there any alternate ways as I have read the eval function is not prefered while coding .js files.

I want some jquery variables to be created dynamically. In my code I am having a loop, and with the loop values I want to create some variables. Here is my sample code.

array=["student","parent","employee"]

$.each(user_types, function( index, value ){
  var value+"_type" // this is the type of variable i want to build.
})

I have found about eval function. That code goes like this.

var type = "type"
eval("var pre_"+type+"= 'The value of dynamic variable, val';");

alert(pre_type) // this gives 'The value of dynamic variable, val' in alert box.

Is there any alternate ways as I have read the eval function is not prefered while coding .js files.

• javascript
• jquery

• 1 duplicate stackoverflow.com/questions/5187530/… – Fabien Sa Commented Nov 14, 2013 at 11:50
• 1 var pres = {}; var type = "foo"; pres[type] = "something"; - "dynamic keys" – user2864740 Commented Nov 14, 2013 at 11:51

3 Answers 3

Any time you find yourself using a variable in the name of a variable, you probably want to use an object literal. Create the object with curly braces {}, and then set the object property key using square bracket notation:

var user_types = ["student","parent","employee"];
var types = {};

$.each(user_types, function( index, value ){
  types[value] = 'The value of dynamic variable, val';
});

JSFiddle

Note: You haven't tagged it, but I assume because you've used each() that you are using jQuery, please correct me if I'm wrong.

First of all i must say that i can't think of any reason why you want to do this.

If you really need to have those variables, in global scope, you can do the following:

var array=["student","parent","employee"]

array.forEach(function(value){
  window[value+"_type"] = 'My value ' + value;
});

console.log(student_type);
console.log(parent_type);
console.log(employee_type);

If you don't want the variables in global scope, i'm afraid i don't know an elegant solution.

I used array.forEach instead of your jQuery loop because the problem is not related to jQuery at all and because i don't think you said enough of your logic to make a coherent example.

EDIT: I should make it clear that while the 'variables' created behave mostly like other variables in global scope, they are NOT variables. Here is how they differ:

// Difference 1: hoisting
console.log(x); // undefined
console.log(y); // ReferenceError: y is not defined
var x = 5;
window[y] = 5;
console.log(x); // 5
console.log(y); // 5
// Difference 2: [[Configurable]] 
delete x;
delete y;
console.log(x); // 5
console.log(y); // ReferenceError: y is not defined

If you want to add an intermediate variable inside the string, you can do it as follows:

var itemSelect: number = 1;
$(`#tab${this.itemSelect}-tab`).tab('show');
/* Result -> $(`#tab1-tab`).tab('show');  */

/* HTML */
<a id="tb1-tab"> </a>