There are an array of objects found eligible subjects (find methods After finding the object is not qualified to perform in the future)
without qualifying returns undefined
var ARR = [ {name: 'Jerry', Sex: 'man' }, {name: 'Jack', Sex: 'Woman' }, {name: 'Jack', Sex: 'man' } ] var Jack = ARR .find ( function (obj) { return obj.name == 'Jack' ; }) the console.log (Jack); // returns first object qualified {name: "jack", sex : "woman"} var Bill = arr.find ( function (obj) { return obj.name == 'Bill' ; }) Console. log(bill); // undefined