indexOf的方法是返回所检索字符串或者字符所在的位置(也可以说是下标,所检索的下标是从0开始,检索的起始位也是从0开始); 如果检索的是字符串,则是返回字符串首个字符的下标开始; 语法 stringObject.indexOf(searchvalue,fromindex) 1varstr = "this is this first"2varcc = str.indexOf("this");//=>03cc...
for(var item of array){ if (item == “third”) { break; } alert(item);// first,sencond } 6)for in 用来遍历对象属性(使用for in会遍历数组所有的可枚举属性,包括原型) 定义:用于循环遍历数组或对象属性,fot in循环里面的index是string类型的, 代码每执行一次,就会对数组的元素或者对象的属性进行一...
const indexOfFirst = paragraph.indexOf(searchTerm); console.log(`The index of the first "${searchTerm}" from the beginning is ${indexOfFirst}`); // Expected output: "The index of the first "dog" from the beginning is 40" console.log(`The index of the 2nd "${searchTerm}" is ${...
3.lastIndexOf()()方法 lastIndexOf() 方法用于查找数组中某个元素最后一次出现的索引(位置),如果找到则返回该索引值,否则返回 -1。 const fruits = ['火龙果', '橘子', '蓝莓', '西瓜', '葡萄', '橘子']; console.log(fruits.lastIndexOf('橘子'));//5console.log(fruits.lastIndexOf('柚子'))...
JS对象 indexOf() 方法可返回某个指定的字符串值在字符串中首次出现的位置。 2016-06-15 08:49 −... 攻城狮-云上 0 2206 js获取时间差值 2019-12-23 23:00 −1 function GetTime(firstDate, secondDate) { 2 // 1.对时间进行处理 3 var firsttime = Date.parse(firstDate + " 00:00:00"...
if(error){constp=PromiseReject(error);// Only the first element errorserror=null;returnp;}// {3} 如果迭代器对象完成,Promise.resolve done 设置为 trueif(finished){returnPromiseResolve(createIterResult(undefined,true));}// {4} 等待直到一个事件发生returnnewPromise(function(resolve,reject){...
constnlBEFormatter=newIntl.DateTimeFormat('nl-BE');console.log(nlBEFormatter.format(firstValentineOfTheDecade));// 14/2/2020 1. 2. 3. 或者美国格式的较长形式,并拼写出月份名称: 复制 constlongEnUSFormatter=newIntl.DateTimeFormat('en-US',{year:'numeric',month:'long',day:'numeric',});conso...
firstA1 = firstA1 + 1; //默认计算的位数实际是到a的前一位,所以+1才是a的所处位置 var endA1 = str.lastIndexOf('a') endA1 = endA1 + 1; //同上 //带参数 var firstA2 = str.indexOf('a',5); firstA2 = firstA2 + 1; //默认计算的位数实际是到a的前一位,所以+1才是a的所处位置...
if (!String.prototype.includes) { String.prototype.includes = function(search, start) { 'use strict'; if (typeof start !== 'number') { start = 0; } if (start + search.length > this.length) { return false; } else { return this.indexOf(search, start) !== -1; ...
First, we need to create the Mongoose schema in/users/models/users.model.js: constuserSchema =newSchema({firstName:String,lastName:String,email:String,password:String,permissionLevel:Number}); Once we define the schema, we can easily attach the schema to the user model. ...