如何阻止此文本键入动画循环

Question

我不明白是什么让这个动画一次又一次地开始，以及播放一次后如何停止。有人能帮帮我吗？为了找出代码的哪一部分负责循环，我逐一删除了代码的不同部分，看看结果会受到什么影响，但我仍然找不到

这是HTML:

<a href="" class="typewrite" data-period="2000" data-type='[ "Hello.", "My name is B.", "I am just starting with  HTML, CSS and JavaScript.", "Please bear with me..."]'>
<span class="wrap"></span>
</a>

这是JavaScript：

var TxtType = function(el, toRotate, period) {
this.toRotate = toRotate;
this.el = el;
this.loopNum = 0;
this.period = parseInt(period, 10) || 2000;
this.txt = '';
this.tick();
this.isDeleting = false;
};
TxtType.prototype.tick = function() {
var i = this.loopNum % this.toRotate.length;
var fullTxt = this.toRotate[i];
if (this.isDeleting) {
this.txt = fullTxt.substring(0, this.txt.length - 1);
} else {
this.txt = fullTxt.substring(0, this.txt.length + 1);
}
this.el.innerHTML = '<span class="wrap">'+this.txt+'</span>';
var that = this;
var delta = 200 - Math.random() * 100;
if (this.isDeleting) { delta /= 2; }
if (!this.isDeleting && this.txt === fullTxt) {
delta = this.period;
this.isDeleting = true;
} else if (this.isDeleting && this.txt === '') {
this.isDeleting = false;
this.loopNum++;
delta = 500;
}
setTimeout(function() {
that.tick();
}, delta);
};
window.onload = function() {
var elements = document.getElementsByClassName('typewrite');
for (var i=0; i<elements.length; i++) {
var toRotate = elements[i].getAttribute('data-type');
var period = elements[i].getAttribute('data-period');
if (toRotate) {
new TxtType(elements[i], JSON.parse(toRotate), period);
}
}
// INJECT CSS
var css = document.createElement("style");
css.type = "text/css";
css.innerHTML = ".typewrite > .wrap { border-right: 0.08em solid #f6fd96}";
document.body.appendChild(css);
};

Answer 1

u使用递归每隔delta ms调用tick((函数。这就是环路所在的位置。

TxtType.prototype.tick = function() {
// ...
setTimeout(function() {
that.tick();
}, delta);
}

如果您只想此代码一次。请添加递归的停止条件。

if (this.loopNum < this.toRotate.length) {
setTimeout(function() {
that.tick();
}, delta);
}

Answer 2

动画循环发生在TxtType.prototype.tick函数的末尾，当函数再次递归调用自己时：

setTimeout(function() {
that.tick();
}, delta)

setTimeout是一个在一段时间后运行某些内容的函数。在这种情况下，它在delta时间之后运行that.tick()。

如果你想让它只循环一次，你可以使用this.loopNum信息来围绕上面的那些行设置一个条件：

if(this.loopNum < 1) {
setTimeout(function() {
that.tick();
}, delta)
}