javascript - Calling function within prototype object - Stack Overflow

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How can I call PrintIt foo from Set()? I get error that it can't find it...
I know it's possible to call it via MyObject.prototype.PrintIt but this way i will "lose" the object and it's property (Num)

MyObject = function(){           
    this.Num=6;            
}


MyObject.prototype = {
    initialize: function(){     
        document.getElementById("button1").onclick = this.Set;
    },
    Set: function(){
        this.PrintIt();
    },                                
    PrintIt: function(){
        alert("I Print"); 
        //alert( this.Num);                       
    }                
}

window.onload = function(){              
    obj = new MyObject;
    obj.initialize();                                
}

How can I call PrintIt foo from Set()? I get error that it can't find it...
I know it's possible to call it via MyObject.prototype.PrintIt but this way i will "lose" the object and it's property (Num)

MyObject = function(){           
    this.Num=6;            
}


MyObject.prototype = {
    initialize: function(){     
        document.getElementById("button1").onclick = this.Set;
    },
    Set: function(){
        this.PrintIt();
    },                                
    PrintIt: function(){
        alert("I Print"); 
        //alert( this.Num);                       
    }                
}

window.onload = function(){              
    obj = new MyObject;
    obj.initialize();                                
}

• javascript

Share Improve this question Follow edited Nov 10, 2010 at 8:44 Felix Kling 818k181181 gold badges1.1k1.1k silver badges1.2k1.2k bronze badges asked Nov 10, 2010 at 8:36 shlomjmishlomjmi 69733 gold badges1212 silver badges1616 bronze badges 0

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1 Answer 1

Sorted by: Reset to default 7

The problem lies not in the prototype but in the way how you assign the method to the click handler. There it loses its connection to the object. You can use a closure:

initialize: function(){
    var that = this;     
    document.getElementById("button1").onclick = function(){
        that.Set();
    };
},

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