笔记-实现find方法

var arr = [
    {id:1,name:'张三'},
    {id:2,name:'李四'},
    {id:3,name:'王五'},
    {id:4,name:'刘八'},
]

Array.prototype.myFind = function(fn){
    for(var i = 0; i<this.length ; i++){
        if(fn(this[i],i)){
            return this[i]
        }
    }
}

var ret  = arr.myFind(function(item,index){
    return item.id === 4
})