``` var obj = ['AA','BB','CC','DD','AA','BB','11',11] //定义一个新的数组 var s = []; //遍历数组 for(var i=0;i<obj.length;i++){ if(s.indexOf(obj[i]) == -1){ //判断在s数组中是否存在，不存在则push到s数组中 s.push(obj[i]); } } console.log(s); ``` ``` var old_data = [ { name: 'ccc', age: '28' }, { name: 'peng', age: '28' }, { name: 'aaa', age: '28' }, { name: 'peng', age: '28' }, ] // 方法1：利用对象访问属性的方法，判断对象中是否存在key var result = []; var obj = {}; old_data.forEach(function (data) { if(!obj[data.name]){ result.push(data); obj[data.name] = true; } }) console.log(result); ``` > 根据数组某个字段相同，修改另外字段值 ``` var oldData = [ { name: 'cccc', age: '5656' }, { name: 'cccc', age: '22dddsada' }, { name: 'cccc', age: '22dddsada' }, { name: 'aaaa', age: '32' }, { name: 'aaaa', age: '2dasdasdas2' }, ] var newArr = []; for (var i = 0; i < oldData.length; i++) { var item = oldData[i]; var isExists = false; for (var j = 0; j < newArr.length; j++) { var item2 = newArr[j]; if (item2.name == item.name) { isExists = true; break; } } if (isExists) { // 这里找到相同的，更改一样的 if(item.name == 'cccc'){ item.age = '222222' item2.age = '222222' }else{ item.age = '3333' item2.age = '3333' } newArr.push(item2); continue; } newArr.push(item); } console.log(newArr) ```