js判断数组中是否包含某个元素

方法1:arr.indexOf(element):判断数组中是否存在某个值,如果存在,则返回数组元素的下标(第一个元素),否则返回-1;

let fruits = ["Banana", "Orange", "Apple", "Mango"]
let a = fruits.indexOf("Apple")
console.log(a)  // 2

方法2:array.includes(searcElement[,fromIndex]):判断数组中是否存在某个值,如果存在返回true,否则返回false;

let fruits = ["Banana", "Orange", "Apple", "Mango"]
if(fruits.includes("Apple")){
  console.log("存在")
}else {
  console.log("不存在")
}

方法3:arr.find(callback[,thisArg]):返回数组中满足条件的第一个元素的值,如果没有,返回undefined;

let fruits = ["Banana", "Orange", "Apple", "Mango"]
let result = fruits.find(item =>{
    return item == "Apple"
})
console.log(result)  // Apple

方法4:array.findIndex(callback[,thisArg]):返回数组中满足条件的第一个元素的下标,如果没有找到,返回-1

let fruits = ["Banana", "Orange", "Apple", "Mango"]
let result = fruits.findIndex(item =>{
    return item == "Apple"
})
console.log(result)  // 2

方法5:for():遍历数组,然后 if 判断;

let fruits = ["Banana", "Orange", "Apple", "Mango"]
for(v of fruits){
  if(v == "Apple"){
    console.log("包含该元素")
  }
}

方法6:forEach

let fruits = ["Banana", "Orange", "Apple", "Mango"]
fruits.forEach((v)=>{
  if(v == "Apple"){
    console.log("包含该元素")
  }
})
posted @ 2021-05-31 17:17  叶子玉  阅读(6064)  评论(0编辑  收藏  举报