CODEWITHSUNDEEP
javascript
Pingpong
Pingpong

Reputation: 8009

Avoid using global variables and functions in Javascript

How to alter the JavaScript code below so that it can avoid exposing the variables and functions to the global scope?

var nMax = 10;
var i = 0;
var step = function(){
                //do stuff
                i += 1;
                if(i < nMax){
                                step();
                }else{
                                alert('finished');
                }
}
step();

Ideally it would be grateful if the reason behind it could be provided.

Any idea would be very much appreciated!

Upvotes: 1

Views: 837

Answers (4)

QuentinUK
QuentinUK

Reputation: 3077

Put in an object so fn gets called via that:-

 var stepHolder = {};
 stepHolder.step = (function(nMax){
 var i = 0;
 return function step(){
            //do stuff
             i += 1;
            if(i < nMax){
                            step();
            }else{
                            alert('finished');
            }
  };}
  )(10);

    stepHolder.step();

Upvotes: 0

Matt Ball
Matt Ball

Reputation: 359776

An alternative to using a closure: functions are objects, so you can attach values to them just like any other object:

function step()
{
    step.i++;

    if (step.i < step.nMax) step();
    else alert('finished');
}

step();

Or, use an object to namespace the function and variables:

var stepper = 
{
    i: 0,
    nMax: 10,
    step: function ()
    {
        this.i++;

        if (this.i < this.nMax) this.step();
        else alert('finished');
    }
};

stepper.step();

And here's a cleaner version of @PaulPRO's answer which uses a function declaration rather than a function expression:

(function ()
{
    var i = 0,
        nMax = 10;

    function step()
    {
        i++;

        if (i < nMax) step();
        else alert('finished');
    }

    step();
})();

Upvotes: 1

Michael Lorton
Michael Lorton

Reputation: 44376

The standard way would be

var step = function(){
  var nMax = 10;
  var i = 0;
  return function() {
                //do stuff
                i += 1;
                if(i < nMax){
                                step();
                }else{
                                alert('finished');
                }
  };
}();
step();

Upvotes: 2

Paul
Paul

Reputation: 141829

Just wrap it in an anonymous function, and call that function immediately:

(function(){
    var nMax = 10;
    var i = 0;
    var step = function(){
                    //do stuff
                    i += 1;
                    if(i < nMax){
                                    step();
                    }else{
                                    alert('finished');
                    }
    }
    step();
})();

Another Example: http://jsfiddle.net/n5Srd/

Upvotes: 4

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