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  • Common array methods in JavaScript
    Below are some array functions that are commonly required in order to complete Coderbyte challenges. You can view a longer list of JavaScript array functions here.

    indexOf

    Return the index of a specific element in the array. If the element does not exist in the array, the function returns -1.
    var arr = [1, 2, 100, 12, -1];
    
    arr.indexOf(100); // 2
    arr.indexOf(5); // -1
    

    push and pop

    Push elements to the end of the array and delete the last element from an array.
    var arr = [1, 2, 3, 4];
    
    arr.push(5) // [1, 2, 3, 4, 5]
    arr.push(6, 7, 8); // [1, 2, 3, 4, 5, 6, 7, 8]
    
    arr.pop(); // [1, 2, 3, 4, 5, 6, 7]
    

    shift and unshift

    Remove the first element from an array and return that element or add an element to the front of an array.
    var arr = [1, 2, 100, 12, -1];
    
    var first = arr.shift(); // 1
    // arr is now => [2, 100, 12, -1]
    
    arr.unshift(5000); // arr is now => [5000, 2, 100, 12, -1]
    

    reverse

    Reverse the elements in an array.
    var arr = [1, 2, 100, 12, -1];
    arr.reverse(); // [-1, 12, 100, 2, 1]
    

    sort

    Sort the elements in an array based on a compare function.
    var arr = [1, 2, 100, 12, -1];
    
    // sort in ascending order
    arr.sort(function(a, b) { return a - b; }); // [-1, 1, 2, 12, 100]
    
    // sort in descending order
    arr.sort(function(a, b) { return b - a; }); // [100, 12, 2, 1, -1]
    

    slice

    Return a part of the array specified by two numbers, the start and end indices.
    var arr = [1, 2, 100, 12, -1];
    var cutArr = arr.slice(1, 3); // [2, 100]
    
    mrdaniel wrote this tutorial on 1/3/16 | javascript, array
    Comments
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  • Awesome intro to some of the many methods array's have! Another good source is regex methods on arrays. ;)
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  • sort() is making sort by the string unicode To sort numbers, or to make customized sorting, It allows using a callback function as a parameter which is working as follwing:
    /* 
    for each two numbers in the array
    
    *  if function return is positive, sort asc
    *  if function return is negative, sort desc
    *  if function return is zero, don't sort 
    */
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  • I do not understand why this function has to return an ascending order? thanks for the explanation: arr.sort(function(a, b) { return a - b; });
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  • Poor explanation of sort
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  • Which algorithm does it use to sort an array?
    arr.sort(function(a, b) { return a - b; });
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