indexOf is used to search for a value or reference inside of an array. In this lesson we first look at what values are returned when a search is successful vs when it's unsuccessful. Then we move onto a technique that shows how to use the return value to create a boolean flag that ...
JavaScript Array indexOf() 方法JavaScript Array 对象实例 查找数组中的 "Apple" 元素: var fruits = ["Banana", "Orange", "Apple", "Mango"]; var a = fruits.indexOf("Apple"); a 结果输出: 2 以上输出结果意味着 "Apple" 元素位于数组中的第 3 个位置。 尝试一下 » ...
indexOf is used to search for a value or reference inside of an array. In this lesson we first look at what values are returned when a search is successful vs when it's unsuccessful. Then we move onto a technique that shows how to use the return value to create a boolean flag that ...
Returns the first index at which a given element can be found in the array, or -1 if it is not present. Method ofArray Syntax array.indexOf(searchElement[,fromIndex]) Parameters searchElement Element to locate in the array. fromIndex The index at which to begin the search. Defaults to 0...
JavaScript原生数组Array常用方法 原生js中操作数组的方法 1.push() 语法:数组.push(数据) 作用:将数据追加到数组的末尾 返回值:追加数据后数组最新的长度 //准备一个原始数组 var arr=[100,200,300,400] //输出一次 console.log(arr) //执行 push 方法...
JavaScript Array lastIndexOf() 方法JavaScript Array 对象实例 查找数组元素 "Apple"出现的位置: var fruits = ["Banana", "Orange", "Apple", "Mango"]; var a = fruits.lastIndexOf("Apple"); a 输出结果: 2 以上实例输出结果意味着 "Apple" 位于数组中的第 2 个位置. 尝试一下 » ...
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indexOf(2); // 0 array.indexOf(7); // -1 array.indexOf(9, 2); // 2 array.indexOf(2, -1); // -1 array.indexOf(2, -3); // 0 你没法使用 indexOf() 来搜索 NaN。 jsCopy to Clipboard const array = [NaN]; array.indexOf(NaN); // -1 ...
JavaScript Array.shift() Method It is the opposite of unshift method. Using this method, we can remove the elements from the starting of the array. Syntax: array.shift()// No ParameterCode language:JavaScript(javascript) // Exampleconstprime = [1,2,3,5,7] ...
The indexOf() method returns the first index at which a given element can be found in the array, or -1 if it is not present.