window.onload=function(){
var lis = document.getElementByTagName('li');
lis[0].style.backgroundColor = 'gold';
lis[1].style.backgroundColor = 'gold';
}
- document.getElementsByTagName(),标签获取元素
循环
1.for 循环
window.onload= function(){
var olist = document.getElementById('list01');
var ali = olist.getElementsByTagName('li');
for(var i=0;i<8;i++){
if(i%2 == 0){
ali[i].style.backgroundColor = 'gold';
}
}
i++;
}
2.while循环
var i=0;
while (i<ali.length){
if(i%2==0){
ali[i].style.backgroundColor='gold';
}
i++;
}
3.do while循环
var i = 0;
do{
if(i%2==0){
ali[i].style.backgroundColor = 'gold';
}
i++;{
while(i< ali.length);
}
}
- while 和 do while的区别;
- do while是大括号里无论如何都先执行一次，才执行判断是否成立
- while是先判断是否成立，然后在执行大括号里的内容
