JS: Hide variable for other scripts

Question

In scriptA I have this code:

var John = 'Doe';

and in scriptB:

alert(John);

But I don't want that the variables between the 2 scripts are shared, how can I hide the John variable for scriptB? Thanks in advance!

http://stackoverflow.com/questions/500431/what-is-the-scope-of-variables-in-javascript — Popnoodles, Jan 18 '16 at 18:21

score 0 · Answer 1 · answered Jan 18 '16 at 18:23

You can "hide" variables by putting them inside an IIFE (immediately invoked function expression) like this:

(function() {
    // this variable is only accessible within this function block
    var John = "Doe";
})();

// this causes an error because the variable John is not available outside the IIFE
alert(John);

This creates a private function scope which is immediately executed. This is a common design pattern for declaring variables which have local use, but you don't want broadly shared and you don't want to pollute or conflict with the global namespace.

score 0 · Accepted Answer · answered Jan 18 '16 at 18:23

You can use anonymous functions to hide variables:

<script>
    (function(){
        var John = 'Doe';
    })();
</script>

A similar block can be repeated but variable can have different value in that block:

<script>
    (function(){
        var John = 'AnotherValue';
    })();
</script>

JS: Hide variable for other scripts

2 Answers2