问题描述:

JavaScript:

var chop1 = document.getElementById("chop1");

var hit = document.getElementById("butn");

chop1.style.position = "relative";

chop1.style.top = "0px";

var chopperY;

function fly()

{

chop1.style.top = parseInt(chop1.style.top ) + 10 + 'px';

chopperY = chop1.style.top;

if( chopperY == 500)

{

alert("get the position")

}

requestAnimationFrame(fly);

};

hit.onclick = function()

{

fly();

};

In the above example nothing is alerted at chopperY == 500.Console doesn't give any error.What is error in this code?How to alert that string at the given condition?

网友答案:

The style.top property of an HTML node is always a string containing both the position and the unit (in your case it would be a 'px'), so in your conditional statement you should rather write if (chop1 === '500px') {...}.

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