Hook a function in place of existing function in javascript

I am trying to override one function by replacing it with a different version. The function which I am trying to override is defined in a web resource of a control. But, I have tried the same for script resources, it works.

function HookCalendarFunction() {
    try {
        var Original_performLayout = _performLayout;
        _performLayout = function () {
            performLayout();
        };
        var Original_cell_onclick = _cell_onclick;
        _cell_onclick = function (val) {
            cellClick(val);
        };
    }
    catch (e) {

    }

}

Here, _performLayout is a function for a custom control in ASP.net. _performLayout is in web res开发者_运维知识库ources of the control.

Thanks Ashwani

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Check _performLayout is global and your that declaration happens after the original declaration.

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I solved the issue, the issue was with the scope of function.