arr.in_array('test');//判断 test 字符串是否存在于 arr 数组中,存在返回true 否则false,此处将返回true 3.indexOf() function IsInArray(arr,val){ var testStr= ',' +arr.join( "," )+ "," ; return testStr.indexOf( "," +val+ "," )!=-1; } 1. 2. 3. 4. 5. 6. 7. 用法如...
Element to locate in the array. fromIndex The index at which to begin the search. Defaults to 0, i.e. the whole array will be searched. If the index is greater than or equal to the length of the array, -1 is returned, i.e. the array will not be searched. If negative, it is ...
我从myarray.indexOf(element) 得到 -1,即使元素似乎在 myarray 中。 下面是一些代码片段: {代码...} 警报显示 nds 确实包含 el,但警报应该只在 idx==-1 时触发,只有当 nds 不包含 el 时才会触发。 我知道我...
if(!Array.prototype.lastIndexOf){Array.prototype.lastIndexOf=function(searchElement/*, fromIndex*/){'use strict';if(this===void0||this===null){thrownewTypeError();}varn,k,t=Object(this),len=t.length>>>0;if(len===0){return-1;}n=len-1;if(arguments.length>1){n=Number(arguments[1...
array.IndexOf()是JavaScript中的一个数组方法,用于返回指定元素在数组中首次出现的索引位置。如果数组中不存在该元素,则返回-1。 该方法的语法如下: array.IndexOf(element, start) 参数说明: element:要查找的元素。 start(可选):指定开始查找的索引位置,默认为0。
var obj = {prop: [element0, element1, …, elementN]} 1. 如果你希望用单个元素初始化一个数组,而这个元素恰好又是数字(Number),那么你必须使用括号语法。当单个的数字(Number)传递给Array()构造函数时,将会被解释为数组长度,并非单个元素。 var arr = [42]; // 创建一个只有唯一元素的数组: ...
functionisBigEnough(element) {returnelement >= 15; }varret1 = [12, 5, 8, 130, 44].findIndex(isBigEnough); console.log(ret1);//index of 4th element in the Array is returned,//so this will result in '3'varobjArr = [{id:1, name:'jiankian'}, {id:23, name:'anan'}, {id:...
array[index], if used in an expression, or on the right hand side of the assignment operator, fetches the element of the array at specified index. In the following example, we take an array with three elements, and read the element at index2. ...
fill()Fill the elements in an array with a static value filter()Creates a new array with every element in an array that pass a test find()Returns the value of the first element in an array that pass a test findIndex()Returns the index of the first element in an array that pass a ...
indexOf() && lastIndexOf()这两个方法,也推荐放在一起看,他们都是返回在数组中找到给定元素的索引,区别是一个从左边寻找,一个从右边寻找。如果找不到,则返回 -1 。与includes() 方法一样,都接收 fromIndex 参数,可以从指定索引处开始查找。const array = ['🐨', '🐯', '🦁'] array.indexOf('...