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CSS3里怎么实现打字动画

php中世界最好的语言asal: 2017-11-25 14:32:241661semak imbas

相较于之前的CSS版本，我们利用css3可以实现很多炫酷的东西，比如老版的CSS无法实现的打字动画。下面我们就给大家带来一个小案例，看看酷炫的打字动画是怎么做出来的。

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8" />
    <title>Document</title>
    <style type="text/css" media="screen">
        .box {
            width:100%;
            height:500px;
            text-align:center;
            position:relative;
        }
        .container {
            width:80%;
            height:400px;
            border:1px solid red;
            text-align:left;
            margin:0 auto;
        }
        .container span {
            display:inline-block;
            border:1px solid red;
            transition: all 2s;
            transform:translateY(0px) rotate(0deg);
            font-size:14px;
        }
        textarea {
            width:200px;
            resize:none;
            height:20px;
            line-height:20px;
            padding:10px 0px;
            font-size:14px;
            font-weight:400;
        }
        .clone {
            font-size:14px;
            border:1px solid red;
            width:80%;
            height:20px;
            margin:0 auto;
            line-height:20px;
            padding:10px 0px;
            text-align:left;
            visibility:hidden;
        }
        .clone span {
            transition:all 2s;
            position:absolute;
        }
 
    </style>
</head>
<body>
    <div>
        <div>
 
        </div>
        <div>
            <span></span>
        </div>
        <textarea placeholder="请输入文字"></textarea>
    </div>
</body>
    <script>
    //计算出input输入框的偏移值
    var container = document.querySelector(".container");
    var inner = document.querySelector(".inner");
    var clone = document.querySelector(".clone");
    var textarea = document.querySelector(".textarea");
    var offx = (container.offsetWidth - textarea.offsetWidth-20)/2;
    var offy = (container.offsetHeight + inner.offsetHeight);
 
        //创造一个span标签 需要注入需要注入起始坐标
        function createspan(text,x,y) {
           this.text = text;
           this.x = x;
           this.y = y;
           this.init = {};
        }
        createspan.prototype.render = function() {
            var span = document.createElement("span");
            container.appendChild(span);
            span.style.display = "inline-block";
            span.style.transform = "translateX("+this.x+"px) translateY("+this.y+"px) rotate(720deg)";
            span.style.transition = "all 2s";
            span.innerHTML = this.text;
            this.init = span;
        }
        createspan.prototype.recover = function() {
            var that = this;
            setTimeout(function(){
                that.init.style.transform = "translateX(0px) translateY(0px) rotate(0deg)";
            },10)
        }
        var newtext = "";
        var oldtext = "";
        var x = 0;
        var y = 0;
        var total = "";
        //监听textarea文本框的输入变化情况
        textarea.addEventListener("input",function(){
            var text = "";
            if (inner.offsetWidth >= container.offsetWidth ) {
                offx = (container.offsetWidth - textarea.offsetWidth-20)/2 - textarea.offsetWidth;
            }
            else if (inner.offsetWidth >= textarea.offsetWidth*3) {
                offx = (container.offsetWidth - textarea.offsetWidth-20)/2 - textarea.offsetWidth*3;
            }
             else if (inner.offsetWidth >= textarea.offsetWidth*2) {
                offx = (container.offsetWidth - textarea.offsetWidth-20)/2 - textarea.offsetWidth*2;
            } else if(inner.offsetWidth>=textarea.offsetWidth) {
                offx = (container.offsetWidth - textarea.offsetWidth-20)/2 - textarea.offsetWidth;
            }
 
            //先算文字的变化 两种情况一种是增加一种是减少
            newtext = textarea.value;
            oldtext = inner.innerHTML;
            newtext = newtext.trim();
            //添加字符
            if(newtext.length > oldtext.length) {
                for(var i = 0;i < newtext.length;i++) {
                    if(newtext[i] != oldtext[i]) {
                       text += newtext[i];
                        inner.innerHTML = newtext;
                    }
                }
                total += text;
                // 生成
                    for(var i =0;i < text.length;i++) {
 
                        var a = new createspan(text[i],offx,offy);
                        a.render();
                        a.recover();
                    }
            }
            //删除字符
 
        })
    </script>
</html>

相信通过这个案列大家会熟练的掌握CSS3的这个功能，更多精彩请关注php中文网其它相关文章！

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