Asynchronous Callbacks

Async2.js

function logItem(item) {
    console.log(item);
}

function asyncEach3(arr, callback) {
    // Utility inner function to create a wrapper function for the callback
    function makeCallbackWrapper(arr, i, callback) {
        // Create our function scope for use inside the loop
        return function() {
            callback(arr[i]);
        }
    }

    for (var i = 0; i < arr.length; ++i) {
        setTimeout(makeCallbackWrapper(arr, i, callback), 0);
    }
}

console.log("begin");
asyncEach3([1, 2, 3], logItem);
console.log("end");

Asynchronous1.js

function logItem(item) {
    console.log(item);
}

function asyncEach3(arr, callback) {
    // Utility inner function to create a wrapper function for the callback
    function makeCallbackWrapper(arr, i, callback) {
        // Create our function scope for use inside the loop
        return function() {
            callback(arr[i]);
        }
    }

    for (var i = 0; i < arr.length; ++i) {
        setTimeout(makeCallbackWrapper(arr, i, callback), 0);
    }
}

console.log("begin");
asyncEach3([1, 2, 3], logItem);
console.log("end");