Common Methods for Javascript array objects

<SCRIPT type = "text/JavaScript"> // shift: deletes the first entry of the original array and returns the value of the deleted element. If the array is empty, undefined var arr = [1, 2, 3, 4, 5]; var out = arr. shift (); console. log (ARR); // [2, 3, 4, 5] Console. log (out); // 1 var arr = []; var out = arr. shift (); console. log (ARR); // [] Console. log (out); // undefined // unshift: add the parameter to the beginning of the original array, and return the array length (undefined under IE6) var arr = [1, 2]; vaR out = arr. unshift (-1, 0); console. log (ARR); // [-1, 0, 1, 2] conso Le. log (out); // 4 // POP: Delete the last entry of the original array and return the value of the array to be deleted. If the array is empty, return undefined var arr = [1, 2, 3, 4, 5]; var out = arr. pop (); console. log (ARR); // [1, 2, 3, 4] Console. log (out); // 5 var arr = []; var out = arr. pop (); console. log (ARR); // [] Console. log (out); // undefined // push: add the parameter to the end of the original array, and return the array length var arr = [1, 2, 3]; vaR out = arr. push (4, 5, 6); console. log (ARR); // [1, 2, 3, 4, 5, 6] Console. log (out); // 6 // Concat: return a parameter VaR arr = [1, 2, 3]; var out = arr. concat (4, 5); console. log (ARR); // [1, 2, 3] Console. log (out); // [1, 2, 3, 4, 5] // splice (START, deletecount, val1, val2 ,...): Delete the original array deletecount from the start position, and insert val1, val2 ,..., returns the new array of deleted items var arr = [1, 2, 3, 4, 5]; var out = arr. splice (2, 2, 7, 8, 9, 10); console. log (ARR); // [1, 2, 7, 8, 9, 10, 5] Console. log (out); // [3, 4] // when clearing the array, you only need to pass start. If you do not delete all elements, then pass deletecoun T var arr = [1, 2, 3, 4, 5]; var out = arr. splice (2); console. log (ARR); // [1, 2] Console. log (out); // [3, 4, 5] // same shift var arr = [1, 2, 3, 4, 5]; var out = arr. splice (0, 1); console. log (ARR); // [2, 3, 4, 5] Console. log (out); // [1] // same as unshift var arr = [1, 2, 3, 4, 5]; var out = arr. splice (0, 0, 22,-1, 0); console. log (ARR); // [22,-1, 0, 1, 2, 3, 4, 5] Console. log (out); // [] // same as pop var arr = [1, 2, 3, 4, 5]; VaR out = arr. splice (ARR. length-1, 1); console. log (ARR); // [1, 2, 3, 4] Console. log (out); // [5] // same push var arr = [1, 2, 3, 4, 5]; var out = arr. splice (ARR. length, 0, 6, 7, 8); console. log (ARR); // [1, 2, 3, 4, 5, 6, 7, 8] Console. log (out); // [] // reverse: sorts the original array in reverse order; var arr = ['A', 1, {}, [2, 3]; console. log (ARR); // ['A', 1, {}, [2, 3] var out = arr. reverse (); console. log (ARR); // [[2, 3], {}, 1, 'a'] Console. lo G (out); // [[2, 3], {}, 1, 'a'] var arr = [0, 1, 5, 10, 15]; arr. reverse (); console. log (ARR); // [15, 10, 5, 1, 0] var arr = [1, 0, 5, 15, 10]; arr. reverse (); console. log (ARR); // [10, 15, 5, 0, 1] // sort (orderfunction): Sort () is in ascending order, but the tostring () method of each array item is called first, then compare the strings for sorting, which are compared by ASCII; // different from the reverse principle. When sort () does not contain parameters, it literally sorts the array var arr = [0, 1, 5, 10, 15]; arr. sort (); console. log (ARR); // 0, 1, 10, 15, 5. Note that the character strings are compared by ASCII. // The function sortnumber (, b) {return a-B} arr. sort (sortnumber); console. log (ARR); //, 15 // slice (START, end): return from the original array specified start to end (does not contain this element) if there is only one parameter, VAR arr = [1, 2, 3, 4, 5, 6, 7, 8] From start to the end of the array; vaR out = arr. slice (2, 3); console. log (ARR); // [1, 2, 3, 4, 5, 6, 7, 8] Console. log (out); // [3] // join (separator): combines the elements of the array into a string with the separator, if this parameter is omitted, the default delimiter var arr = [1, 2, 3, 4, 5, 6] is used as the delimiter; var out = arr. join (); console. log (ARR); // [1, 2, 3, 4, 5, 6] Console. log (out); // 1, 2, 3, 4, 5, 6 out = arr. join (""); console. log (out); // 123456 out = arr. join ("&"); console. log (out); // 1 & 2 & 3 & 4 & 5 & 6 </SCRIPT>