The first official account of this article: ELO's cabin, welcome to pay attention and view more content!!!
function
The code block stores a piece of code for processing a single task, and then calls it with a short command whenever necessary
JavaScript has many built-in functions. Browser functions are not part of the core JavaScript language, but are defined as part of the browser API
method
Functions are called part of object methods, and built-in browser functions are not functions -- they are methods
Custom function
Functions defined according to their own requirements
Call function
Call followed by parentheses
function demoFunction() { alert('hi function!'); } demoFunction()
Anonymous function
A function without a name is an anonymous function
function() { alert('no name'); }
Anonymous functions are typically used with event handlers
Function parameters
var demoText = 'I am a boy'; var newText = demoText.replace('boy', 'girl');
'boy' and 'girl' are the parameters of the replace function
Function return value
Refers to the value returned after the function is executed
var demoText = 'I am a string'; var demoString = myText.replace('string', 'demo'); console.log(demoString);
The above content saves the return value as the content of demoString variable
Use return value
Use the return keyword
function randomNumber(number) { return Math.floor(Math.random()*number); }
event
Events are actions or events that occur in the system during programming. The system will generate or trigger certain signals when events occur, and will provide an automatic loading of certain actions. Each available event will have an event processor, which is sometimes called an event listener
object
An object is a collection of related data and methods. To create an object, you usually define initialization variables first
var person = {};
Enrich the object
var person = { name : ['Elo', 'Yiluo'], age : 19, gender : 'male', interests : ['games', 'shopping'], contact : 'Wechat search: ELO's Cabin', greeting: function() { alert('Hi! I\'m ' + this.name[0] + '.'); } };
Then call
person.name[0] person.age person.greeting()
View the result of the call
person.name[0] "Elo" person.age 19 person.greeting ƒ () { alert('Hi! I\'m ' + this.name[0] + '.'); } person.contact; "Wechat search: ELO's Cabin" person.greeting() undefined
Point representation
In the above example, dot notation is used to access the properties and methods of the object. The name of the object must be written first,
Bracket notation
Using bracket notation, objects map strings to values, such as
person['age'] person['name']['age']
Meaning of "this"
The keyword "this" points to the object of the current code runtime.
Prototype language
JavaScript is often described as a prototype based language. To be exact, these attributes and methods are defined on the prototype attribute on the constructor functions of the Object, rather than the Object instance itself
JSON
JSON is a data format based on JavaScript object syntax. JSON can exist as an object or string with the extension of json
JSON structure
demoObj = { "name":"Elo Yiluo", "zone":"Wechat search: ELO's Cabin", "sites": { "site1":"https://yiluotalk.com/", "site2":"https://yiluotalk.com/", "site3":"https://yiluotalk.com/" } }
Welcome to [poke] and [like] below
Author: Yiluo
May you enjoy every day, just joy!