js计时器

// 计时器
var c = 120;
var t;
function changTextTimer() {
var btn = document.getElementById("btnId");
btn.disabled = true;
btn.style.cursor = "";
c = c - 1;
btn.value = "再次发送(" + c + ")";
t = setTimeout("changTextTimer()", 1000);
if (c <= 0) {
clearTimeout(t);
btn.disabled = false;
btn.style.cursor = "pointer";
btn.value = "发送验证";
c = 120;
}

}

效果如下（带倒计时） 用时调用changTextTimer（）即可