Summary of JavaScript knowledge points: Document Object Model-JS Tutorial-php.cn

Summary of JavaScript knowledge points: Document Object Model

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Release： 2021-01-08 14:14:09

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Document Object Model

Common properties of document objects

document.bgColor: page background color
document.fgColor: text The foreground color of
document.title: page title

	
	对象常用属性

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document object finds HTML element

document.getElementById(): Find the specified html page element based on the id
document.getElementsByTagName(): All html page elements with the specified tag name
document.getElementsByName(): All the specified name HTML page elements
document.getElementsByClassName(): Find the specified html page element based on the class name

	
	对象常用属性

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document object changes HTML

document.getElementById().innerHTML=New element
document.getElementById().innerText=New content
document.getElementById().style.property=New Style
document.getElementById().attributes=New Attributes

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DOM Node Operation

document. getElementById().parentNode: The parent node of the current node
document.getElementById().childNodes: All nodes of the current node
document.getElementById().firstChild: The first one of the current node Node
document.getElementById().lastChild: the last node of the current node
document.getElementById().previousSibling: the previous sibling node of the current node
document. getElementById().nextSibling: The next sibling node of the current node
document.createElement(): Add a new node
document.appendChild(): Move the node
document. removeChild(): Delete node

Data object

##var a=new Date(): Current event
a.getDate(): One day of the month
a.getDay(): Each day of the week
a.getFullYear(): Return as four digits Year
a.getHours(): Returns hours
a.getMilliseconds(): Returns milliseconds
a.getMinutes(): Returns minutes
a .getMonth(): Returns the month
a.getSeconds(): Seconds of the meeting
a.getTime(): Returns the number of milliseconds from 1970.1.1 to now

Math object

Math. abs(number): Returns the absolute value of number
Math.ceil(number): Round the number upward, for example, the return value of Math.ceil(67.6) is 68
Math.floor(number): round the number downward, for example, the return value of Math.floor (67.6) is 67
Math.max(number1,number2): Returns the larger value between number1 and number2
Math.min(number1,number2): Returns the smaller value between number1 and number2
Math.pow(x,y): Returns x raised to the power of y
Math.random(): Returns a pseudo-random number between 0 and 1, which may be 0, but is always less than 1, [0,1)
Math.roundd(number): Returns the integer closest to number
Math.sqrt(number): The square root of number

String object
Summary of JavaScript knowledge points: Document Object Model
Create array method

var arr=[1,2,3, "happy"];
var arr=new Array();The initial element of the array is 0
var arr=new Array(4);The initial element of the array is 4
var arr=new Array(1,2,3); Initialize the array with specified elements

##Create object

var 对象名=new 类名（实参1，实参2，实参n）

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Definition Class

function 类名（参数1，参数2...）{
	this.属性=参数1；	this.属性=参数2；	...
	this.方法名=function（）{
		//方法体
	}}

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Commonly used statements for objects

with: To loop through the properties of an object, you can abbreviate the code
for ...in: Loop through all attributes of an object and assign attribute names to temporary variables one by one without knowing the number of object attributes in advance
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