Native js implements class_javascript techniques to find/add/delete/specify elements

Copy code The code is as follows:

window.onload = function(){
var gaga = document .getElementById( "gaga" );
addClass( gaga,"gaga1" )
addClass( gaga,"gaxx" );
removeClass( gaga,"gaga1" )
removeClass( gaga," gaga" )
function hasClass( elements,cName ){
return !!elements.className.match( new RegExp( "(\s|^)" cName "(\s|$)") ); / / ( \s|^ ) Determine whether there is a space in front (s | $) Determine whether there is a space in the back. The two exclamation marks are converted into Boolean values ​​to facilitate judgment
};
function addClass( elements,cName ){
if( !hasClass( elements,cName ) ){
elements.className = " " cName;
};
};
function removeClass( elements,cName ){
if ( hasClass( elements,cName ) ){
elements.className = elements.className.replace( new RegExp( "(\s|^)" cName "(\s|$)" )," " ); // The replace method is to replace
};
};
};