


JavaScript input email automatically prompts example code_javascript skills
I originally wanted to share my previous comments on artTemplate source code analysis, but after a year, I couldn’t find them, so I had to try it myself after analyzing the principles of the template engine at that time
I would like to share the template engine I wrote down with you as a souvenir. I remember that I compared several template engines at that time.
The js template engine mentioned here uses native javascript syntax, so it is very similar to php's native template engine.
What is the role of front-end template engine?
1. It can make front-end development simpler. There is no need to use operators to splice strings in order to generate a DOM structure. Instead, only one element (the HTML template inside) or a variable (which stores the template) is needed. Or a template file
2. Easy to maintain and reduce coupling. If your DOM structure changes, you do not need to change the logic code, but only need to change the corresponding template (file)
3. It can be cached. If your template is a file similar to .tpl, it can be loaded by the browser and still saved. Speaking of .tpl files, you can do more than cache, you can also do it through the module loader
By using .tpl as a module, you can load files on demand. Wouldn’t it save bandwidth and speed up the page?
4. Wait etc
What is the principle of front-end template engine?
The principle is very simple: object (data) + template (containing variables) -> string (html)
How to implement the front-end template engine?
By parsing the template, convert the template into a function according to the lexicon, and then call the function and pass the object (data) to output a string (html)
(Of course, the specific details depend on the code)
Like this:
var tpl = 'i am , years old'; // % Lexical, marked as variable
var obj = {
name : 'lovesueee' ,
Age : 24
};
var fn = Engine.compile(tpl); // Compile into function
var str = fn(obj); // Render out the string
Example:
<script><BR> var trs = [<BR> {name:"隐形杀手",age:29,sex:"男"},<BR> {name:"索拉",age:22,sex:"男"},<BR> {name:"fesyo",age:23,sex:"女"},<BR> {name:"恋妖壶",age:18,sex:"男"},<BR> {name:"竜崎",age:25,sex:"男"},<BR> {name:"你不懂的",age:30,sex:"女"}<BR> ] <P> // var html = ice("tpl",{<BR> // trs: trs,<BR> // href: "http://images.jb51.net/type4.jpg"<BR> // },{<BR> // title: function(){<BR> // return "<p>这是使用视图helper输出的代码片断"<BR> // }<BR> // });<BR> var elem = document.getElementById('tpl');<BR> var tpl = elem.innerHTML; <P> var html = ice(tpl,{<BR> trs: trs,<BR> href: "http://images.jb51.net/type4.jpg"<BR> },{<BR> title: function(){<BR> return "<p>这是使用视图helper输出的代码片断"<BR> }<BR> });<BR> console.log(html);<BR> $("#content").html(html);<br><br></script>
简单的实现:
(function (win) {
// 模板引擎路由函数
var ice = function (id, content) {
return ice[
typeof content === 'object' ? 'render' : 'compile'
].apply(ice, arguments);
};
ice.version = '1.0.0';
// 模板配置
var iConfig = {
openTag : ' closeTag : '%>'
};
var isNewEngine = !!String.prototype.trim;
// 模板缓存
var iCache = ice.cache = {};
// 辅助函数
var iHelper = {
include : function (id, data) {
return iRender(id, data);
},
print : function (str) {
return str;
}
};
// 原型继承
var iExtend = Object.create || function (object) {
function Fn () {};
Fn.prototype = object;
return new Fn;
};
// 模板编译
var iCompile = ice.compile = function (id, tpl, options) {
var cache = null;
id && (cache = iCache[id]);
if (cache) {
return cache;
}
// [id | tpl]
if (typeof tpl !== 'string') {
var elem = document.getElementById(id);
options = tpl;
if (elem) {
// [id, options]
options = tpl;
tpl = elem.value || elem.innerHTML;
} else {
//[tpl, options]
tpl = id;
id = null;
}
}
options = options || {};
var render = iParse(tpl, options);
id && (iCache[id] = render);
return render;
};
// 模板渲染
var iRender = ice.render = function (id, data, options) {
return iCompile(id, options)(data);
};
var iForEach = Array.prototype.forEach ?
function(arr, fn) {
arr.forEach(fn)
} :
function(arr, fn) {
for (var i = 0; i fn(arr[i], i, arr)
}
};
// 模板解析
var iParse = function (tpl, options) {
var html = [];
var js = [];
var openTag = options.openTag || iConfig['openTag'];
var closeTag = options.closeTag || iConfig['closeTag'];
// 根据浏览器采取不同的拼接字符串策略
var replaces = isNewEngine
?["var out='',line=1;", "out+=", ";", "out+=html[", "];", "this.result=out;"]
: ["var out=[],line=1;", "out.push(", ");", "out.push(html[", "]);", "this.result=out.join('');"];
// 函数体
var body = replaces[0];
iForEach(tpl.split(openTag), function(val, i) {
if (!val) {
return;
}
var parts = val.split(closeTag);
var head = parts[0];
var foot = parts[1];
var len = parts.length;
// html
if (len === 1) {
body += replaces[3] + html.length + replaces[4];
html.push(head);
} else {
if (head ) {
// code
// 去除空格
head = head
.replace(/^\s+|\s+$/g, '')
.replace(/[\n\r]+\s*/, '')
// 输出语句
if (head.indexOf('=') === 0) {
head = head.substring(1).replace(/^[\s]+|[\s;]+$/g, '');
body += replaces[1] + head + replaces[2];
} else {
body += head;
}
body = 'line =1;';
js.push(head);
}
// html
if (foot) {
_foot = foot.replace(/^[nr] s*/g, '');
if (!_foot) {
return;
}
body = replaces[3] html.length replaces[4];
html.push(foot);
}
}
});
body = "var Render=function(data){ice.mix(this, data);try{"
body
replaces[5]
"}catch(e){ice.log('rend error : ', line, 'line');ice.log('invalid statement : ', js[line-1]);throw e;}};"
"var proto=Render.prototype=iExtend(iHelper);"
"ice.mix(proto, options);"
"return function(data){return new Render(data).result;};";
var render = new Function('html', 'js', 'iExtend', 'iHelper', 'options', body);
return render(html, js, iExtend, iHelper, options);
};
ice.log = function () {
if (typeof console === 'undefined') {
return;
}
var args = Array.prototype.slice.call(arguments);
console.log.apply && console.log.apply(console, args);
};
// 合并对象
ice.mix = function (target, source) {
for (var key in source) {
if (source.hasOwnProperty(key)) {
target[key] = source[key];
}
}
};
// 注册函数
ice.on = function (name, fn) {
iHelper[name] = fn;
};
// 清除缓存
ice.clearCache = function () {
iCache = {};
};
// 更改配置
ice.set = function (name, value) {
iConfig[name] = value;
};
// 暴露接口
if (typeof module !== 'undefined' && module.exports) {
module.exports = template;
} else {
win.ice = ice;
}
})(window);

JavaScript is widely used in websites, mobile applications, desktop applications and server-side programming. 1) In website development, JavaScript operates DOM together with HTML and CSS to achieve dynamic effects and supports frameworks such as jQuery and React. 2) Through ReactNative and Ionic, JavaScript is used to develop cross-platform mobile applications. 3) The Electron framework enables JavaScript to build desktop applications. 4) Node.js allows JavaScript to run on the server side and supports high concurrent requests.

Python is more suitable for data science and automation, while JavaScript is more suitable for front-end and full-stack development. 1. Python performs well in data science and machine learning, using libraries such as NumPy and Pandas for data processing and modeling. 2. Python is concise and efficient in automation and scripting. 3. JavaScript is indispensable in front-end development and is used to build dynamic web pages and single-page applications. 4. JavaScript plays a role in back-end development through Node.js and supports full-stack development.

C and C play a vital role in the JavaScript engine, mainly used to implement interpreters and JIT compilers. 1) C is used to parse JavaScript source code and generate an abstract syntax tree. 2) C is responsible for generating and executing bytecode. 3) C implements the JIT compiler, optimizes and compiles hot-spot code at runtime, and significantly improves the execution efficiency of JavaScript.

JavaScript's application in the real world includes front-end and back-end development. 1) Display front-end applications by building a TODO list application, involving DOM operations and event processing. 2) Build RESTfulAPI through Node.js and Express to demonstrate back-end applications.

The main uses of JavaScript in web development include client interaction, form verification and asynchronous communication. 1) Dynamic content update and user interaction through DOM operations; 2) Client verification is carried out before the user submits data to improve the user experience; 3) Refreshless communication with the server is achieved through AJAX technology.

Understanding how JavaScript engine works internally is important to developers because it helps write more efficient code and understand performance bottlenecks and optimization strategies. 1) The engine's workflow includes three stages: parsing, compiling and execution; 2) During the execution process, the engine will perform dynamic optimization, such as inline cache and hidden classes; 3) Best practices include avoiding global variables, optimizing loops, using const and lets, and avoiding excessive use of closures.

Python is more suitable for beginners, with a smooth learning curve and concise syntax; JavaScript is suitable for front-end development, with a steep learning curve and flexible syntax. 1. Python syntax is intuitive and suitable for data science and back-end development. 2. JavaScript is flexible and widely used in front-end and server-side programming.

Python and JavaScript have their own advantages and disadvantages in terms of community, libraries and resources. 1) The Python community is friendly and suitable for beginners, but the front-end development resources are not as rich as JavaScript. 2) Python is powerful in data science and machine learning libraries, while JavaScript is better in front-end development libraries and frameworks. 3) Both have rich learning resources, but Python is suitable for starting with official documents, while JavaScript is better with MDNWebDocs. The choice should be based on project needs and personal interests.


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