JS function code collection_javascript skills

1. Imitate fade in(), fade out().

Principle: setInterval ("opacity++transparency" function, time interval)

var alpha = 0;
function play(){
timer = setInterval(function(){
alpha += 2;
alpha > 100 && (alpha = 100);
aImg[index].style.opacity = alpha / 100;
aImg[index].style.filter = "alpha(opacity = " + alpha/100 + ")";
alpha == 100 && clearInterval(timer);
},40)
}

2. Get and set the attribute value of the element object:

Key points: obj.currentStyle[attr]; getComputedStyle(obj,null)[attr];

function css(obj,attr,val) {
switch(arguments.length) {
case 2:
if(typeof arguments[1] == "string"){
return obj.currentStyle ? obj.currentStyle[attr] : getComputedStyle(obj,null)[attr];
}else{
for(var i in attr) {
obj.style[i] = attr[i];
}
}
break;
case 3:
obj.style[attr] = val;
break;
default:
alert("错误参数");
}
}

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