模板引擎

Long long ago, 动态页面的两种渲染方式：

DOM API操作繁琐
innerHTML可读性和可维护性差

于是出现了模板引擎，例如JavaScript Micro-Templating
实现代码如下：

// Simple JavaScript Templating`
// John Resig - [https://johnresig.com/](https://johnresig.com/) 
(function(){
    var cache = {};

    this.tmpl = function tmpl(str, data){
        // Figure out if we're getting a template, or if we need to
        // load the template - and be sure to cache the result.
        var fn = !/\W/.test(str) ?
            cache[str] = cache[str] || tmpl(document.getElementById(str).innerHTML) :

            // Generate a reusable function that will serve as a template
            // generator (and which will be cached).
            new Function("obj",
                "var p=[],print=function(){p.push.apply(p,arguments);};" +

                // Introduce the data as local variables using with(){}
                "with(obj){p.push('" +

                // Convert the template into pure JavaScript
                str
                    .replace(/[\r\t\n]/g, " ")
                    .split("<%").join("\t")
                    .replace(/((^|%>)[^\t]*)'/g, "$1\r")
                    .replace(/\t=(.*?)%>/g, "',$1,'")
                    .split("\t").join("');")
                    .split("%>").join("p.push('")
                    .split("\r").join("\\'")
            + "');}return p.join('');");
            
        // Provide some basic currying to the user
        return data ? fn( data ) : fn;
    };
})();

使用时输写形如下面的代码：

<script type="text/html" id="item_tmpl">
  <div id="<%=id%>" class="<%=(i % 2 == 1 ? " even" : "")%>">
    <div class="grid_1 alpha right">
      <img class="righted" src="<%=profile_image_url%>"/>
    </div>
    <div class="grid_6 omega contents">
      <p><b><a href="/<%=from_user%>"><%=from_user%></a>:</b> <%=text%></p>
    </div>
  </div>
</script>

做到了DOM解构清晰，所见即所得。

模板引擎性能好需要：