Question

I have the following piece of code which is not running as I expected:

var person = new Class({
    initialize: function(name)
    {
        this.personName = name;
        alert(this.personName)        //WORKS :-)

        this.testFunc();              //WORKS :-)
        this.createShape();           //PAINTS SHAPE BUT CANNOT ACCESS 'personName'
    },
    testFunc() : function()
    {
        alert(this.personName);
    }, 
    createShape() : function()
    {
        this.personShape = paper.rect(40,40,40,40).attr({"fill":"blue"});
        $(this.personShape.node).click(function()
        {

            alert(this.personName);
        });
    }
});

The alert doesn’t work for the click event and I do understand its because it cannot access the object variable ‘personName’. I would however like to know whether or not it is possible to access it in some way?

Would there be a neat little Javascript trick to achieve this?

Answer 1

Inside your click function in createShape, the context is being set to this.personShape.node. this no longer refers to your person so it needs to be cached. Try this:

createShape: function() {
    var context = this;
    context.personShape = paper.rect(40,40,40,40).attr({"fill":"blue"});
    $(context.personShape.node).click(function() {
        alert(context.personName);
    });
}

Also, your functions shouldn’t have parenthesis in your Class/object definition. Also, it’s a good idea to start putting your curly braces on the same line as your statement for a few reasons. Here’s my refactor:

var person = new Class({
    initialize: function(name) {
        this.personName = name;
        alert(this.personName)        //WORKS :-)

        this.testFunc();              //WORKS :-)
        this.createShape();
    },
    testFunc: function() {
        alert(this.personName);
    }, 
    createShape: function() {
        var context = this;
        context.personShape = paper.rect(40,40,40,40).attr({"fill":"blue"});
        $(context.personShape.node).click(function() {
            alert(context.personName);
        });
    }
});