简单的jquery选择器的实现
function getByClass(oParent,oClass){
if(document.getElementsByClassName){
return document.getElementsByClassName(oClass);
}else{
var arr=[];
var tag=document.getElementsByTagName(*);
for(var i=0;i<tag.length;i++){
if(tag[i].className==oClass){
arr.push(tag[i]);
}
}
return arr;
}
}
function jquery(selector){
if(selector.substr(0,1)==='#'){
return document.getElementById(selector.substr(1));
}else if(selector.substr(0,1)==='.'){
return getByClass(document,selector);
}else{
return document.getElementsByTagName(selector.substr(1));
}
}