1, by acquiring the elements tag returns an array
document.getElementsByTagName Li = var ( 'Li'); // label acquisition element
li [0] .innerHTML; // view the contents of an Element
Li [0] = .innerHTML "Content"; // modify the contents of the acquired tag
2, access to page elements by id
document.getElementById header = var ( "header"); // Get element ID
3, access to page elements by class name
List document.getElementsByClassName = var ( 'List'); // Returns an array, to access the text by the subscript
4, access to page elements by way of CSS selectors
// querySelector: return the right first
var str = document.querySelector ( 'li' );
document.querySelectorAll str1 = var ( 'li'); // return all, each li is an object
. 1 <! DOCTYPE HTML > 2 < HTML lang = "ZH-CN" > . 3 < head > . 4 < Meta charset = "UTF-. 8" > . 5 < title > the JavaScript common method of obtaining a page </ title > . 6 < Script > 7 // 1, acquired by the tag elements returns an array . 8 var Li = document.getElementsByTagName ( ' Li ' ); . 9 10 // 2, acquired by the page element ID . 11 varheader = document.getElementById ( " header " ); 12 is 13 is // . 3, page acquired by the class name of the element 14 var List = document.getElementsByClassName ( ' List ' ); // Returns an array, indexed access through the text 15 16 / / 4, obtaining a page element by way CSS selectors . 17 // querySelector: returns the first qualifying 18 is var STR = document.querySelector ( ' Li ' ); . 19 // querySelectorAll: a return each qualifying 20 is var str1= document.querySelectorAll('li'); 21 </script> 22 </head> 23 <body> 24 <p id="header">JavaScript学习</p> 25 <ul class="list"> 26 <li>HTML</li> 27 <li>jQuery</li> 28 <>liJavaScript</li> 29 </ul> 30 <ul class="list"> 31 <li>HTML</li> 32 <li>jQuery</li> 33 <li>JavaScript</li> 34 </ul> 35 </body> 36 </html>