findIndex() && find()

最新推荐文章于 2025-06-19 18:09:56 发布

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最新推荐文章于 2025-06-19 18:09:56 发布

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分类专栏： Js 文章标签： findIndex()

本文链接：https://blog.youkuaiyun.com/weixin_42481234/article/details/86702873

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本文通过实例演示了JavaScript中数组方法find和findIndex的使用技巧，详细解析了如何利用这两种方法在数组中查找特定元素及其索引，适用于前端开发场景。

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stu.find((element) => (element.name == '李四'));返回的是{name: "李四", gender: "男", age: 20}这个元素
stu.findIndex((element)=>(element.name =='李四'));返回的是索引下标：2

var arr = [
    {"provCode":null,"count":"16","rgnname":"宁夏"},
    {"provCode":null,"count":"158","rgnname":"山东"},
    {"provCode":null,"count":"8","rgnname":"北京"},
    {"provCode":null,"count":"13","rgnname":"天津"},
    {"provCode":null,"count":"114","rgnname":"河北"},
    {"provCode":null,"count":"66","rgnname":"辽宁"},
    {"provCode":null,"count":"3","rgnname":"西藏"},
    {"provCode":null,"count":"123","rgnname":"河南"},
    {"provCode":null,"count":"56","rgnname":"浙江"},
    {"provCode":null,"count":"126","rgnname":"广西"},            
    {"provCode":null,"count":"273","rgnname":"广东"},                
    {"provCode":null,"count":"115","rgnname":"云南"},
    {"provCode":null,"count":"23","rgnname":"海南"},
    {"provCode":null,"count":"1","rgnname":"四川"}, 
    {"provCode":null,"count":"1094","rgnname":"count"}
]

 //寻找值   存在问题
    for (let i = 0; i < arr.length; i++) {
        console.log(provinceName);                    
        if(provinceName === arr[i].rgnname){                 
            var count = Number(arr[i].count);
            console.log(count,"count");

            var ct = format(count);        //格式转化   
            $("#saleSt span:eq(0)").html(ct);                          
        }
        // else if (provinceName !== arr[i].rgnname) {
        //     // $("#saleSt span:eq(0)").html("0");  
        //     return alert("AAA")  
       // }
    } 

    // 查值               
    function getIndex(params) {
        return params.rgnname == provinceName
    }             
    // arr.find(getIndex)

    var  e = arr.findIndex(getIndex);//返回-1  provinceName不在arr中
    // alert(e)
    if (e !== -1) {
        var count = Number(arr[e].count);
        console.log(count,"count");    
        var ct = format(count);        //格式转化   
        $("#saleSt span:eq(0)").html(ct);    
    }else{
        $("#saleSt span:eq(0)").html("0"); 
    }

https://blog.youkuaiyun.com/menghuannvxia/article/details/79640028

        var arr = [-8,1,2,3,4,5,6,7,8,9];
		var ce = arr.find((n) => n < 0);
		// alert(ce)
        
		var AAA = arr.find(function(value,index,arr){			
			return value == -8;		 // -8	
		})
		var BBB = arr.findIndex(function(value,index,arr){			
			return value == -8;		// 0	
		})
		console.log(AAA,BBB)


		function f(v){
		  return v > this.age;
		}
		let person = {name: 'John', age: 20};

		var CCC = [10, 12, 26, 15].find(f, person);    // 26
		var DDD = [10, 12, 26, 15].findIndex(f, person);    // 2
		console.log(CCC, DDD)