How to write a shift function without splicing

Question

I am trying to write functions for some basic array methods, but now I'm stuck on re-creating the shift without using splicing. Any advice would be greatly appreciated.

MyShift = function (array) {
    for (i = array.length - 2; i >= 0; i--) {
        array[i] = array[i + 1];
    }
    --array.length;
};

Answer 1

Due to the way you iterate, you change the value iwith i+1and then move backward, so you assign the last value to all positions

MyShift = function(array) {
  for (var i = 0; i < array.length - 1; i++) {
    array[i] = array[i + 1];
  };
  --array.length;
};

var a = ['a', 'b', 'c'];
MyShift(a);
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, , i=1, array[1] = array[2], [a, c, c], i=0, array[0] = array[1], arra[1], [c,c,c]

MyShift = function(array) {
  snippet.log('src: ' + array)
  for (i = array.length - 2; i >= 0; i--) {
    array[i] = array[i + 1];
    snippet.log('loop ' + i + ': ' + array);
  }
  --array.length;
};

var a = ['a', 'b', 'c'];
MyShift(a);
snippet.log('Result: ' + a)

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Answer 2

Array.prototype.shift().

. .

https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Array/shift

Answer 3

You can do something like this.

MyShift = function (array) {
    for (i =0; i<array.length; i++) {
        array[i] = array[i + 1];
        console.log(array[i]);
    }
    --array.length;
    return(array);
}; 
MyShift([1,2,3,4]);

Hope this helps