函数节流防抖

// 节流函数
function throttle(fn, delay){
var t = null,
begin = new Date().getTime();

return function(){
var _self = this,
args = arguments,
cur = new Date().getTime();

clearTimeout(t);

if(cur - begin >= delay){
fn.apply(_self, args);
begin = cur;
}else{
t = setTimeout(function(){
fn.apply(_self, args);
}, delay);
}
}
}