array within class does not retain scope????

**anupshinde** · 2 Nov 2011 9:08 PM

Hi,

The following code uses ExtJS4. I have created a custom class and defined a variable as an array.For two different instances of the class "a" and "b" the values are getting shared.

(1) The first array variable is defined as elements: []. The add method adds to the elements

(2) The second array variable is defined as elements: null. While adding I check if it is null then create a new array before pushing.

With (1) the array elements between both the instances get shared. I would like to understand why (1) does not work as expected.

Any insights will be helpful.

Thanks,
Anup.

Code:

<html>


<head>
<script type="text/javascript" charset="utf-8" src="http://cdn.sencha.io/ext-4.0.7-gpl/ext-all.js"></script>
<script>


Ext.define('MyClass',{
    className: '',
    elements1: [],
    elements2: null,
    add : function(obj) {
        if(this.elements2==null) this.elements2 = new Array();
        this.elements1.push(obj);
        this.elements2.push(obj);
    },
    
    displayCount : function() {
        alert('Elements 1 length: ' +this.elements1.length);
    },


    displayCount2 : function() {
        alert('Elements 2 length: ' +this.elements2.length);
    },
    
    nothing: null


});




Ext.onReady(function () {


    a = new MyClass();
    b = new MyClass();
    
    a.className='Object A';
    a.add(1);
    a.add(2);
    a.add(3);
        
    b.className='Object B';
    b.add(4);
    b.add(5);
    
    a.displayCount(); // displays 5 for elements1 -- shouldn't it be 3
    b.displayCount(); // displays 5 for elements1 -- shouldn't it be 2


    
    a.displayCount2(); // displays 3 correctly
    b.displayCount2(); // displays 2 correctly
    
});


</script>
<head>
<body></body>
</html>

**tvanzoelen** · 2 Nov 2011 11:59 PM

you must re-initialize your arrays in the constructor. See http://www.sencha.com/forum/showthre...someway-global

**tvanzoelen** · 3 Nov 2011 12:02 AM

Like

Code:

Ext.define('MyClass',{
    className: '',
    elements1: [],
    elements2: null,

    constructor: function(config){
    
    this.elements1 = [];
    this.elements2 = [];   

} ,    

    add : function(obj) {
        if(this.elements2==null) this.elements2 = new Array();
        this.elements1.push(obj);
        this.elements2.push(obj);
    },
    
    displayCount : function() {
        alert('Elements 1 length: ' +this.elements1.length);
    },


    displayCount2 : function() {
        alert('Elements 2 length: ' +this.elements2.length);
    },
    
    nothing: null


});




Ext.onReady(function () {


    a = new MyClass();
    b = new MyClass();
    
    a.className='Object A';
    a.add(1);
    a.add(2);
    a.add(3);
        
    b.className='Object B';
    b.add(4);
    b.add(5);
    
    a.displayCount(); // displays 5 for elements1 -- shouldn't it be 3
    b.displayCount(); // displays 5 for elements1 -- shouldn't it be 2


    
    a.displayCount2(); // displays 3 correctly
    b.displayCount2(); // displays 2 correctly
    
});

array within class does not retain scope????

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