javascript （用setTimeout而非setInterval）

var num = 0; 
var max = 10; 
function incrementNumber() { 
num++; 
//if the max has not been reached, set another timeout 
if (num < max) { 
setTimeout(incrementNumber, 500); 
} else { 
alert(“Done”); 
} 
} 
setTimeout(incrementNumber, 500);

如果用setInterval 可能出现 下次调用会在前一次调用前调用 （

True intervals are rarely used in production environments because it ' s possible that one interval will begin before the previous one has finished executing）