本文为工具方法，提供简单但常用的js方法函数。

方法代码

function findIndexByKeyValue(arr, key, valuetosearch) {for (var i = 0; i < arr.length; i++) {if (arr[i][key] == valuetosearch) {return i;}}return -1;}

使用示例

var arr =[{"rollnumber": 1,"name": "dj","subject": "physics"},{"rollnumber": 2,"name": "tanmay","subject": "biology"},{"rollnumber": 3,"name": "amit","subject": "chemistry"}];if(findIndexByKeyValue(arr, 'name', 'tanmay') != -1){console.log('tanmay存在');} else{console.log('tanmay不存在');}