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Learning about array, object method, and array equality judgment Array method forEach() The forEach() method executes the given function once for each element of the array. const array1 = ['a', 'b', 'c']; array1.forEach(element => console.log(element)); // "a" // "b" // "c" Use arr.forEach(callback(currentValue [, index [, array]])[, ...

1. Definition and invocation of functions How 1.1 functions are defined 1. Function Declarations function Keyword (named function) 2. Function expression (anonymous function) 3. new Function() var fn=new Function('Parameter 1', 'Parameter 2', 'Parameter 3'..., 'Function Body') - Function Inside parameters must be in string format - The third ...

Understanding prototypes and prototype chains This article will use concepts + exercises to help understand concept Before we understand the prototype, let's talk about constructors and using constructors to create objects Constructor and create instance for instance: An ordinary Person function is defined, which is still an ordinary func ...

object Concise expression of attributes let name = "Lucy" let age = 16 let s = "school" let obj = { name, age, s:"PKU" } console.log(obj) // Output {name: "Lucy", age: 16, s: "PKU"} Property name expression let name = "Lucy" let age = 16 let s = "school" let obj = { name, age, [s]:"PKU" } console.log(o ...

         Webpack is a front-end resource modular management and packaging tool. The webpack.config configuration file contains entry files, exit files, loader loader and plugin plug-ins         Package directly through the webpack command on the console The followin ...

1, Remaining parameters 1. Understanding residual parameters The remaining parameters are always arrays, even if there are no values, they are empty arrays // grammar const add = (x, y, ...args) => { console.log(x, y, args) // w 4 [5,45] } add('w', 4, 5, 45) 2. Remaining parameter considerations ...

1. Data type and type conversion (1) Data type and typeof() The following basic data types are provided in JavaScript String string Number value Boolean     Boolean type null     empty undefined   Undefined typeof (dat) can get the data type of the specified data (2) Type conversion 1. Convert to numeric typ ...

Core concept of React (2)   1. Component introduction and props   1.1 component classification   Component, conceptually similar to JavaScript functions. It accepts any input parameter (i.e. "props") and returns the React element used to describe the content of the page presentation( Quoted from: Components & props )   Compo ...

ECMAScript 6 adds a Set set type to bring a Set data structure to the language. Sets are like enhanced maps in many ways because most of their API s and behaviors are common. 6.6.1 basic API You can create an empty collection using the new keyword and the Set constructor. If you want to initialize the instance while creating, you can pass an ...

Catalog Prototype Chain inherit Why does Javascript not have a method signature? Prototype Chain Inheritance Constructor Inheritance Combinatorial Inheritance Prototype Inheritance Parasitic Inheritance Parasitic combinatorial inheritance Prototype Chain A prototype chain is a relationship between a prototype object and an instanc ...