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What is var

Posted on 2012-03-31
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Last Modified: 2012-04-02
Im trying to debug a few javascripts, and wondering if there is a way of finding out if a var is a string, int, long, float etc?

For example, if I use:-
var x=5;
var carname="Volvo";

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Is it possible to detect what x is stored as, or carname?
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Question by:tonelm54
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6 Comments
 
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Accepted Solution

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leakim971 earned 500 total points
ID: 37791038
vars are not typed (you can change their type at any moment),  you may use typeof keyword to know the current type of a var : https://developer.mozilla.org/en/JavaScript/Reference/Operators/typeof

var x=5;
alert( "type of x is " + typeof x);
var carname="Volvo";
alert( "type of x is " + typeof carname);

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test page : http://jsfiddle.net/2VLW4/
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Expert Comment

by:Dave Baldwin
ID: 37792518
"You declare JavaScript variables with the var keyword:"  http://www.w3schools.com/js/js_variables.asp
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Expert Comment

by:Proculopsis
ID: 37792572
Noooooo, var is used to define a local variable - see below:

hello = "Hello ";
world = "World!"

function sample() {
    hello = "Goodnight ";
    var world = "Vienna!";
}

new sample();
alert( hello + world ); // => Goodnight World!

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Expert Comment

by:Lee Savidge
ID: 37794953
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Expert Comment

by:Anuradha Goli
ID: 37795583
var simple refers to variable means it can be changed during the code.
You can get data type of variable using typeof.
Example:

  <script type="text/javascript">
        var firstname;
        firstname=12;
        document.write(typeof(firstname));
        document.write("<br />");
        firstname="Tove";
        document.write(firstname);
    </script>

returns number,
If firstname="12" then it returns string
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Expert Comment

by:Lee Savidge
ID: 37795622
The question asker isn't asking what "var" is. The query is with respect to finding out the type which you can use typeof to determine that.
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