Javascript Array Operations

Shift: Delete the first entry of the original array and return the value of the deleted element. If the array is empty, return undefined var a = [1, 2, 3, 4, 5]; var B =. shift (); // a: [2, 3, 4, 5] B: 1 unshift: add the parameter to the beginning of the original array, and return the array length var a = [1, 2, 3, 4, 5]; var B =. unshift (-2,-1); // a: [-2,-,] B: 7 Note: In IE6.0, the returned value is always undefined, the test return value in FF2.0 is 7, so the return value of this method is not reliable. You need to use splice instead of this method when returning the value. Pop: Delete the last entry of the original array and return the value of the deleted element. If the array is empty, return undefined var a = [1, 2, 3, 4, 5]; var B =. pop (); // a: [,] B: 5 push: add the parameter to the end of the original array, and return the array length var a =, 5]; var B =. push (6, 7); // a: [1, 3, 4, 5, 6, 7] B: 7 concat: returns a new array, is to add parameters to the original array to form var a = [1, 2, 3, 4, 5]; var B =. concat (); // a: [, 5] B: [, 7] slice () was originally used to capture a part of the array, here I use it to copy the array. Its format is as follows: array. slice (start, end) if the end parameter is omitted, the split array contains all elements from start to end of the array. Now we need to use it to copy the array, just one line: var newArray = oldArray. slice (0); splice (start, deleteCount, val1, val2 ,...): Delete the deleteCount item from the start position, and insert val1, val2 ,... var a = [1, 2, 3, 4, 5]; var B =. splice (, 9); // a: [,] B: [] var B =. splice (0, 1); // same as shift. splice (0, 0,-2,-1); var B =. length; // same as unshift var B =. splice (. length-1, 1); // same as pop. splice (. length, 0, 6, 7); var B =. length; // same as push reverse: returns the reverse order of the array var a = [1, 2, 3, 4, 5]; var B =. reverse (); // a: [5, 4, 3, 2, 1] B: [5, 4, 3, 2, 1] sort (orderfunction ): sort the array by the specified parameter var a = [1, 2, 3, 4, 5]; var B =. sort (); // a: [1, 2, 3, 4, 5] B: [1, 2, 3, 4, 5] slice (start, end ): returns the array var a = [1, 2, 4, 5]; var B =. slice (); // a: [, 5] B: [, 5] join (separator): groups the elements of the array into a string, use separator as the separator, otherwise use the default comma as the separator var a = [1, 2, 4, 5]; var B =. join ("|"); // a: [1, 2, 3, 4, 5] B: "1 | 2 | 3 | 4 | 5"