var a = ['1'];a[5] = 52;a.length //這兒的結(jié)果是6，也就是說，中間的key會自動補全，而值呢，是undefined

test = {}; //空json對像test['firstname'] = "tank"; //添加二個元素test['lastname'] = "zhang";console.log(test); //查看delete test['lastname']; //刪除json中的某個元素console.log(test);

test1 = [{"name":"tank","total":"100"},{"name":"zhang","total":"23"},{"name":"hao","total":"325"}];add = {"name":"may"};test1.push(add); //添加一個元素console.log(test1);delete test1[2]; //刪除一個元素console.log(test1);

test = ["100","23","325"]; //定義個數(shù)組function sortNumber(a,b) //定義排序方法{   return a - b}test1_sort=test.sort(sortNumber);console.log(test1_sort);

test1 = [{"name":"tank","total":"100"},{"name":"zhang","total":"23"},{"name":"hao","total":"325"}];sort_by = function(field, reverse, primer){ //定義排序方法  var key = primer ?    function(x) {return primer(x[field])} :    function(x) {return x[field]};  reverse = [-1, 1][+!!reverse];  return function (a, b) {    return a = key(a), b = key(b), reverse * ((a > b) - (b > a));   }}test1_sort=test1.sort(sort_by('total', true, parseInt)); //根據(jù)total，升序排console.log(test1_sort);test1_sort=test1.sort(sort_by('name', false, '')); //根據(jù)name，倒序排console.log(test1_sort);