manifest.json 应用配置 | uni-app官网
根据文档上描述需要自定义模板的场景为：
起初以为是在原有的index.html基础上再新建一个html文件，最后发现不是，而是赋值文档里面的hmlt模板基础代码覆盖之前的index.html中的所有代码。
之前uniapp创建的h5项目中index.html 文件代码如下：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<script>
var coverSupport = 'CSS' in window && typeof CSS.supports === 'function' && (CSS.supports('top: env(a)') ||
CSS.supports('top: constant(a)'))
document.write(
'<meta name="viewport" content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0' +
(coverSupport ? ', viewport-fit=cover' : '') + '" />')
</script>
<title></title>
<!--preload-links-->
<!--app-context-->
</head>
<body>
<div id="app"><!--app-html--></div>
<script type="module" src="/main.js"></script>
</body>
</html>使用文档里的html代码覆盖，并通过script标签引入第三方js
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<title>
<%= htmlWebpackPlugin.options.title %>
</title>
<!-- Open Graph data -->
<!-- <meta property="og:title" content="Title Here" /> -->
<!-- <meta property="og:url" content="http://www.example.com/" /> -->
<!-- <meta property="og:image" content="http://example.com/image.jpg" /> -->
<!-- <meta property="og:description" content="Description Here" /> -->
<script>
var coverSupport = 'CSS' in window && typeof CSS.supports === 'function' && (CSS.supports('top: env(a)') || CSS.supports('top: constant(a)'))
document.write('<meta name="viewport" content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0' + (coverSupport ? ', viewport-fit=cover' : '') +
'" />')
</script>
<script src="https://xxxxxx第三方.js"></script>
<link rel="stylesheet" href="<%= BASE_URL %>static/index.<%= VUE_APP_INDEX_CSS_HASH %>.css" />
</head>
<body>
<noscript>
<strong>Please enable JavaScript to continue.</strong>
</noscript>
<div id="app"></div>
<!-- built files will be auto injected -->
</body>
</html>在manifest.json里配置"template": "index.html" 就好啦
