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javascriptscopeiife

iife javascript variable lifetime

how come a variables value within the immediate scope of an iife, survives in a similar way to a global variable in terms of holding it's value. This is really confusing me.

(function(){
    var display = document.getElementById('display');
    var button = document.getElementById('button');
    var count = 0;
    display.innerHTML = 0;

    button.onclick = function(){
        count ++;
        display.innerHTML = count;
    }
})();
Solution

  • It survives because there's still a reference to it in one of your HTMLElements.

    When you attach that lambda to the button.onclick property, there is a reference to count inside the lambda.

    So long as that HTMLElement survives, or that onclick property remains assigned to that lambda, then count will survive too.