段落的展开收起(substring的应用)

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    border:10px solid #ccc;
    background:#FFC;
    width:400px;
    padding:20px;
    font-size:16px;
    font-family:微软雅黑;
    margin:40px auto 0;
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<script>
window.onload = function () {
    var oP = document.getElementsByTagName('p')[0];
    var oSpan = oP.getElementsByTagName('span')[0];
    var oA = oP.getElementsByTagName('a')[0];
    var str = oSpan.innerHTML;
    var onOff = true;
    oA.onclick = function () {
        if ( onOff ) {
            oSpan.innerHTML = str.substring(0, 18);
            oA.innerHTML = '>>展开';
        } else {
            oSpan.innerHTML = str;
            oA.innerHTML = '>>收缩';
        }
        onOff = !onOff;
    };
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<p><span>妙味课堂是一支独具特色的IT培训团队,妙味反对传统IT教育枯燥乏味的教学模式,妙味提供一种全新的快乐学习方法!<br />
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原文地址:https://www.cnblogs.com/Xuman0927/p/5436940.html