JavaScript tips

 1 function changecolor(){
 2     var div1bgcolor = document.getElementById(‘div2‘);
 3 
 4     /*if (div1bgcolor.style.backgroundColor ==‘red‘) {
 5         div1bgcolor.style.background = ‘black‘;
 6     }
 7     else{
 8         alert(div1bgcolor.style.background);
 9         div1bgcolor.style.background = ‘yellow‘;*/
10 
11     div1bgcolor.style.background =(div1bgcolor.style.background=="red"?‘black‘:‘yellow‘);
12     }

function changecolor(){
     var div1bgcolor = document.getElementById(‘div2‘);
     if (div1bgcolor.style.background ==‘red‘) 
    div1bgcolor.style.background = ‘black‘;
    else if(div1bgcolor.style.background == ‘black‘)
    div1bgcolor.style.background = ‘green‘;
    else if(div1bgcolor.style.background == ‘green‘)
    div1bgcolor.style.background = ‘yellow‘;
    else if(div1bgcolor.style.background == ‘yellow‘)
    div1bgcolor.style.background = ‘red‘;

    }
//会循环执行，如果不要else  就不会循环执行