In this article we will learn some concepts of JavaScript.
1) getElementsByTagName(“Tag_Name”)
=> document.getElementsByTagName(“p”).length
for(i=0,i<len;i++){
var result = document.getElementsByTagName(“p”)[i]
document.write(result)
}
2) getElementsByClassName(“geek”)
=> getElementsByClassName(“geek color”)
- returns all elements which has both class geek and color
3)document.getElementById(“show”).getElementsByClassName(“geek”)
Var len = getElementsByClassName(“geek”).length
for(let i=0, i<len; i++){
Var result = document.getElementsByClassName(“geek”)[i]
document.write(result)
}
4) querySelector(‘CSS selector’)
- It returns first match of specified selector or group of selectors.
- if no match found it returns null
5) Element selector
=> querySelector(“p”)
=> querySelector(“p, h1”)
6) Id Selector
=> querySelector(“#show1”)
- querySelector(“#show1, #show2”)
7) Class Selector
=> querySelector(“.geek”)
=> querySelector(“p.myclass”)
=> querySelector(“p>span.myclass”)
8) querySelectorAll(“CSS selector”)
9) Element selector
=> querySelectorAll(“p”)
=> querySelectorAll (“p, h1”)
10) Class Selector
=> querySelectorAll (“.geek”)
=> querySelectorAll (“p.myclass”)
=> querySelectorAll (“p>span.myclass”)
11) Attribute Selector
=> querySelectorAll (“div[id]”)
=> querySelectorAll (“div[id=’geek’]”)
document.getElementById(“show”).querySelectorAll(“span.myspan”)
var result = document.querySelectorAll(“#span > .geek > span.myspan”)
var data = document.querySelectorAll(“.geek”)
var len = document.querySelectorAll(“.geek”).length
for(let i=0,i<len; i++){
var result = document. querySelectorAll(“.geek”)[i];
}
12) Web Page Properties
=> document.URL
=> document.domain
=> document.doctype
=> document.title
=> document.head
=> document.body
=> document.all
=> document.images
=> document.links
14) To know web page properties
=> console.dir(document)
15) To know window properties
=> console.dir(window)
