<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
//模板语法
<script type="text/template" id="underscore">
<ul>
<% arr.forEach(function(value,index){%>
<li><%=value%></li>
<%})%>
</ul>
</script>
<script>
//引擎函数
function template(templateString) {
templateString = templateString.replace(/\n/g,"\\n");
var _p="";
var source = "";
var rules = {
value:/<%=([\s\S]+?)%>/,
express:/<%([\s\S]+?)%>/
};
var regexp = new RegExp(rules.value.source +‘|‘+ rules.express.source,‘g‘);
var index = 0;
templateString.replace(regexp,function (match,value,express,offset) {
source += "_p+=‘"+templateString.slice(index,offset)+"‘;";
index = offset + match.length;
if(value){
source += "_p+="+value+";";
}else if(express){
source+= express+"\n";
}
});
source += "_p+=‘"+templateString.slice(index,templateString.length)+"‘;\n";
source = "var _p=‘‘;\nwith(data){\n "+source +";\n}\nreturn _p";
var _render = new Function(
‘data‘,
source
);
return function (data) {
return _render(data)
}
}
var render = template(document.getElementById("underscore").innerHTML);
console.log(render({arr:[11,22,33]}));
</script>
</body>
</html>
原文：https://www.cnblogs.com/changyaoself/p/11698279.html