javascript - 构建 ES6 解析器和字符串生成器

Question

我正在为一个个人项目构建一个解析器，我希望在实现最初的目标后将其开源。我在动态构建 DOM 时遇到了一些递归调用问题。我根本不想使用任何框架来执行此操作。

基本上，我的代码生成器从 Javascript 数组构建 DOM 字符串来表示 DOM，并使用对象来模拟元素本身。

  var example = [{elm: 'div',
  class: 'fadeIn',
  inner: 'Hello!'}]

会产生

  <div class="fadeIn">Hello!</div>

还有

  var module = [{elm: 'div',   
  class: 'background-yellow',
  inner: example 
  }]

会产生

<div class="background-yellow">
  <div class="fadeIn">Hello!</div>
</div>

我下面的代码相对较好地生成了第一个示例，尽管我已经记录了一些内容以使其完整(例如自闭合标签)。我正在努力解决的部分是代表嵌套节点的嵌套对象。我的目标是递归地执行此操作，但请随意使用迭代方法 - 如果您能提供帮助，我该评判谁:)

// Start with a single node
var testDom = [{
    elm: 'button',
    inner: 'click me!',
    class: 'test-elm',
    onclick: 'javascript:alert("woot!");',
}]

var nestedTest = [{
    elm: 'div',
    inner: testDom
}]

// Define
class parser {

    // This is the parser for JSML
    constructor(stdIn) {
        this.output = '';
        this.parse(stdIn);
        return this.output;
    }

    generateAttributeKeyValueString(key, value) {
        return `${key}='${value}'`;
    }

    generateDom(vNode, nestedOpenTag, nestedCloseTag) {
        var self = this,
            elmStart = `<${vNode.elm}`,
            elmEnd = `</${vNode.elm}>`,
            elmAttrs = '',
            elmContent;
        function parseInput(vNode, key) {
            // if (!vNode.hasOwnProperty(key)) return;
            var value = vNode[key];
            // custom types conditons depending on the key and value of the nodes contents
            var isActualInnerValueChildContents = (key === 'inner' && typeof value !== 'object');
            var isChildrenContentArr = (key === 'inner' && Array.isArray(value));
            var isAttributeKeyValuePair = (key !== 'elm' && key !== 'inner');

            if (isActualInnerValueChildContents) elmContent = value;
            else if (isAttributeKeyValuePair) elmAttrs += self.generateAttributeKeyValueString(key, value); // Otherwise its an attribute and value pair and should be added to the node string
            else if (isChildrenContentArr) {
                // Array of nested child nodes.
                elmStart += ` ${elmAttrs}>`;
                self.generateDom(value, elmStart, elmEnd)
            }
        }   

        for (var key in vNode) parseInput(vNode, key);

        elmStart += ` ${elmAttrs}>`; // Close off the html elements start tag now that all possible attributes have been written



        if (nestedOpenTag && nestedCloseTag) this.output = nestedOpenTag + this.output + nestedCloseTag;
        else this.output = elmStart + elmContent + elmEnd;
    }

    parse(input) {
        var self = this;
        input.forEach((vNode) => {
            self.generateDom(vNode);
        });
    }

}

parser.execute = function(vDom) {
    document.getElementsByTagName('html')[0].innerHTML += vDom.output;
    return vDom;
}

// Call
console.log(parser.execute(new parser(testDom)).output);

这是一个 link显示在单个节点上运行的代码。

预先感谢任何可以提供帮助的人。

Answer 1

我发现了一些事情:

解决主要问题

当您获得inner时值只是纯文本，您可以将元素的内容 ( elmContent ) 设置为该文本

当您获得inner时value 是另一个元素，我的理解是您想要获取该元素的解析版本，并将该元素的内容设置为结果文本。

要获取另一个元素的解析版本，您可以定期解析它并执行 parser.execute(new parser(<element>)).output

所以在 generateDom ，只需设置 elmContent至parser.execute(new parser(value)).output当value是另一个元素，就像您将其设置为 value 一样当value是常规文本。而不是这样做:

if (isChildrenContentArr) {
    // Array of nested child nodes.
    elmStart += ` ${elmAttrs}>`;
    self.generateDom(value, elmStart, elmEnd)
}

这样做:

if (isChildrenContentArr) {
    // Array of nested child nodes.
    elmContent = parser.execute(new parser(value)).output
}

你甚至不需要考虑递归。请记住，您将元素内容设置为 value , 已解析

generateDOM 的最后两个参数从未使用过，因此请像这样删除它们:

generateDom(vNode) { ...

解析多个 DOM 元素的内容

应用上述修复将使您的某些元素正常工作，其中 inner内容只是一个子元素，如

var nestedTest = [{
    elm: 'div',
    inner: testDom
}]

但在其他情况下，它是一个数组，例如

var app = [{
    elm: 'body',
    inner: [
        header,
        content,
        footer
    ]
}]

我注意到的另一件事是所有这些元素都在数组中。我认为你假设数组变平，所以像

[ [element1], [element2], [element3] ]

变成了

[element1, element2, element3]

但是，这在 javascript 中不会发生，您最终会得到一个包含其他数组的数组。因此，当您应用上述代码和value时是一组元素，而不仅仅是一个元素，它不起作用。

首先，您可能应该删除元素周围的所有数组，因此像这样的元素

var app = [{
    elm: 'body',
    inner: [
        header,
        content,
        footer
    ]
}]

变成了

var app = {
    elm: 'body',
    inner: [
        header,
        content,
        footer
    ]
}

(请注意定义周围缺少 [...])

要允许您的解析器解析这些内容，只需更改 parse在您的 parser 中运行至:

parse(input) {
    var self = this;
    self.generateDom(input);
}

然后，处理 value 的情况为一个元素时，单独为多个元素时；分配 value 时在parseInput ，添加isSingleChildContent做:

var value = vNode[key],
// custom types conditons depending on the key and value of the nodes contents
isActualInnerValueChildContents = (key === 'inner' && typeof value === 'string'),
isChildrenContentArr = (key === 'inner' && Array.isArray(value)),
isSingleChildContent = (key === 'inner' && !isChildrenContentArr && (typeof value === 'object')),
isAttributeKeyValuePair = (key !== 'elm' && key !== 'inner');

注意如何 isActualInnerValueChildContents如果 value 则为真是一个字符串，而不仅仅是任何非对象值。 isChildrenContentArr如果 value 则为真是一个数组，就像以前一样。和isSingleChildContent ，新测试，如果 value 则为真。是一个对象而不是数组，它将是单个元素(已删除所有元素变量周围的 [...] )。

现在，如果 inner value是单个元素，elmContent将是解析的元素( parser.execute(new parser(value)).output )。但如果它是多个值，则必须枚举每个值并将其结果添加到 elmContent ，像这样:

//Array of multiple child nodes
elmContent = "";

value.forEach((subValue) => {
    elmContent += parser.execute(new parser(subValue)).output;
});

<小时/>

这是最终的代码片段。这应该适用于您的所有元素(不过我只测试了几个):

/** JSML - Javascript markup language

	Benifits over traditional HTML:
		1) Remove 1 of 3 languages you must know in order to work on the front end of websites (HTML), drastically reducing the complexity of web development
		2) HTML is not flexible, JSML is as flexible as can be
		3) Much tinier syntax compared to HTML, each DOM node is represented by a simple JSON object the DOM is an array no closing tags needed either
		4) Dynamically manipulate elements with no extra frameworks needed - just use plain JS
		5) Framework and platform independant, works with 100% client side and server side libraries out there (it doesnt change anything other than your development process).
		6) Completely manage DOM elements by name instead of selector (very powerful)
		
		Major milestones remaining for v1
		1) Recursive algorithm (right now only generates a single layer of non-nested nodes)
		2) Handling for - seperated data-attributes (camelCase to hyphen-case)
		3) Consistancy between sever and client event assignment
		4) Handling for self closing tags
**/

// Input (language syntax example for static and dynamic)

// Static vNode with dynamic contents
var navigation = {
	elm: 'navigation',
	inner: menuItems(),
	class: 'navigation'
}

// Example of managing the element without explicitly describing the selector more than one time

function sampleMethodBinding(){
	alert();
}

// Dynamically created vNodes
function menuItems() {
	var items = []
	var data = [{
		elm: 'a',
		inner: 'Click here!'
	}, {
		elm: 'a',
		inner: 'here too!'
	}]

	data.forEach(function(itemData, idx) {items.push({
		elm: itemData.elm,
		href: '/page' + idx + '.html',
		inner: 'Nav item #' + idx,
	})});

	return items;
}

var header = {
	elm: 'header',
	inner: navigation,
	class: 'header'
}

var content = {
	elm: 'body',
	inner: 'This is the content area!!!',
	class: 'content'
}

var footer = {
	elm: 'footer',
	inner: navigation,
	class: 'footer'
}

// This is the virtual DOM parent
var app = {
	elm: 'body',
	inner: [
		header,
		content,
		footer
	]
}

// Start with a single node
var testDom = {
	elm: 'button',
	inner: 'click me!',
	class: 'test-elm',
	onclick: 'javascript:alert("woot!");',
}

var nestedTest = {
	elm: 'div',
	inner: testDom
}

// Define
class parser {

	// This is the parser for JSML
	constructor(stdIn) {
		this.output = '';
		this.parse(stdIn);
		return this.output;
	}

	generateAttributeKeyValueString(key, value) {
		return `${key}='${value}'`;
	}

	generateDom(vNode) {
		var self = this,
			elmStart = `<${vNode.elm}`,
			elmEnd = `</${vNode.elm}>`,
			elmAttrs = '',
			elmContent;
		function parseInput(vNode, key) {
				if (!vNode.hasOwnProperty(key)) return;
				var value = vNode[key],
				// custom types conditons depending on the key and value of the nodes contents
				isActualInnerValueChildContents = (key === 'inner' && typeof value === 'string'),
				isChildrenContentArr = (key === 'inner' && Array.isArray(value)),
				isSingleChildContent = (key === 'inner' && !isChildrenContentArr && (typeof value === 'object')),
			    isAttributeKeyValuePair = (key !== 'elm' && key !== 'inner');

			if (isActualInnerValueChildContents) elmContent = value;
			else if (isAttributeKeyValuePair) elmAttrs += self.generateAttributeKeyValueString(key, value); // Otherwise its an attribute and value pair and should be added to the node string
			else if (isChildrenContentArr) {
				//Array of multiple child nodes
				elmContent = "";
				
				value.forEach(function(subValue) {
					elmContent += parser.execute(new parser(subValue)).output;
				});
			} else if (isSingleChildContent) {
				// Just one child node
				elmContent = parser.execute(new parser(value)).output;
			}
			
		}	

		for (var key in vNode) parseInput(vNode, key);

		elmStart += ` ${elmAttrs}>`; // Close off the html elements start tag now that all possible attributes have been written
		
		this.output = elmStart + elmContent + elmEnd;
	}

	parse(input) {
		var self = this;
		self.generateDom(input);
	}

}

parser.execute = function(vDom) {
	document.getElementsByTagName('html')[0].innerHTML += vDom.output;
	return vDom;
}

// Call
document.innerHtml = parser.execute(new parser(app)).output;

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>