Question

Here is my test code that I would like to work.

    function test() {
        var val = 'var ref',
            tobj = new testObj(this);

        tobj.alertParentVal(); //alert 'var ref'
        val = 'new val';
        tobj.alertParentVal(); //alert 'new val'
    }
    function testObj(o) {
       this.alertParentVal = function() {
            alert(o.val);
        }
    }

Without passing the values of ‘val’ to the new testObj, how can I reference ‘val’. If this is not possible. Is there a way to keep a reference to the test() functions variable so that if the value changes in the function I can use the new value in the object.

Answer 1

Variables aren’t accessible as properites, except for on the global object.

You’d need to give the object a function that references the variable in order to read it from outside the variable scope…

function test() {
    var val = 'var ref',
        tobj = new testObj(this);

    this.getVal = function() { return val; }; // accessor for the val variable

    tobj.alertParentVal(); //alert 'var ref'
    val = 'new val';
    tobj.alertParentVal(); //alert 'new val'


}
function testObj(o) {
   this.alertParentVal = function() {
        alert(o.getVal()); // get the variable
    }
}

DEMO: http://jsfiddle.net/a2HfG/1/