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| 1 | +# 选择器 |
| 2 | + |
| 3 | +* 常用的jQuery选择器接口 |
| 4 | + |
| 5 | +* 选择器接口源码解析 |
| 6 | + |
| 7 | +> jQuery对象和DOM对象区别 |
| 8 | +
|
| 9 | +DOM对象 | jQuery对象 |
| 10 | +------------ | ------------- |
| 11 | +是由宿主环境提供的对象.在文档对象模型中,每个部分都是节点 如:所有的HTML元素节点,而element对象表示HTML元素 | jQuery构造函数创建出来的对象 通过jQuery选择器可以获取HTML的元素,并且以一种类数组的形式存储在jQuery对象中 |
| 12 | + |
| 13 | +> 错误的用法与对象转换 |
| 14 | +
|
| 15 | +`````JavaScript |
| 16 | +//错误用法示例代码 |
| 17 | +$('div').innerHTML |
| 18 | +//错误用法示例代码 |
| 19 | +document.getElementsByTagName('div')[0].html() |
| 20 | +//Element对象转换成jQuery对象 |
| 21 | +var domObj = document.getElementById('id'); |
| 22 | +var $obj - $(domObj);//jQuery对象 |
| 23 | +//jQuery对象转换成Element对象 |
| 24 | +var $box = $('.box') |
| 25 | +var box = $box[0] |
| 26 | +````` |
| 27 | + |
| 28 | +> 常用的jQuery选择器接口 |
| 29 | +
|
| 30 | +````javaScript |
| 31 | +//传入对象 |
| 32 | +$(this) |
| 33 | +$(document) |
| 34 | +把传入的对象包装成jQuery对象 |
| 35 | +//传入函数 |
| 36 | +$(function(){}) |
| 37 | +这个是在也买你DOM文档加载完成后在家执行的,等效于在DOM加载完毕后执行$(document).ready()方法 |
| 38 | +//传入字符串 |
| 39 | +$(".box") |
| 40 | +查找DOM节点包装成jQuery对象 |
| 41 | +//空 |
| 42 | +$() |
| 43 | +创建jQuery对象 |
| 44 | +```` |
| 45 | + |
| 46 | + |
| 47 | + |
| 48 | +>jQuery示例对象length属性的作用 |
| 49 | +
|
| 50 | +> merge方法的应用场景有哪些 |
| 51 | +
|
| 52 | +> $(document).ready() 于$(function(){})的关系 |
| 53 | +
|
| 54 | +````html |
| 55 | +<!DOCTYPE html> |
| 56 | +<html> |
| 57 | + <head> |
| 58 | + <meta charset="utf-8"> |
| 59 | + <title></title> |
| 60 | + </head> |
| 61 | + <body> |
| 62 | + <div id="box"></div> |
| 63 | + <script src="jQuery.1.0.1.js"></script> |
| 64 | + <script> |
| 65 | + console.log($("<a>")) //创建DOM |
| 66 | + console.log($("#box")) //查找 |
| 67 | + console.log($(document))//创建 |
| 68 | + </script> |
| 69 | + </body> |
| 70 | +</html> |
| 71 | +```` |
| 72 | +> 如何把创建的DOM节点包装成jQuery对象? |
| 73 | + |
| 74 | + |
| 75 | + |
| 76 | +````JavaScript |
| 77 | +// 调用$("<a>") 其实实在调用 jQuery的init方法 |
| 78 | +(function(root) { |
| 79 | + var testExp = /^\s*(<[\w\W]+>)[^>]*$/; |
| 80 | + var rejectExp = /^<(\w+)\s*\/?>(?:<\/\1>|)$/; |
| 81 | + var version = "1.0.1"; |
| 82 | + var jQuery = function(selector, context) { |
| 83 | + return new jQuery.prototype.init(selector, context); |
| 84 | + } |
| 85 | + |
| 86 | + jQuery.fn = jQuery.prototype = { //原型对象 |
| 87 | + length: 0, |
| 88 | + jquery: version, |
| 89 | + selector: "", |
| 90 | + init: function(selector, context) { |
| 91 | + context = context || document; |
| 92 | + var match, elem, index = 0; |
| 93 | + //$() $(undefined) $(null) $(false) |
| 94 | + if (!selector) { |
| 95 | + return this; |
| 96 | + } |
| 97 | + |
| 98 | + if (typeof selector === "string") { |
| 99 | + if (selector.charAt(0) === "<" && selector.charAt(selector.length - 1) === ">" && selector.length >= 3) { |
| 100 | + match = [selector] |
| 101 | + console.log(match,1) |
| 102 | + } |
| 103 | + //创建DOM |
| 104 | + if (match) { |
| 105 | + //this |
| 106 | + console.log(this) |
| 107 | + jQuery.merge(this, jQuery.parseHTML(selector, context)); |
| 108 | + //查询DOM节点 |
| 109 | + } else { |
| 110 | + elem = document.querySelectorAll(selector); |
| 111 | + var elems = Array.prototype.slice.call(elem); |
| 112 | + this.length = elems.length; |
| 113 | + for (; index < elems.length; index++) { |
| 114 | + this[index] = elems[index]; |
| 115 | + } |
| 116 | + this.context = context; |
| 117 | + this.selector = selector; |
| 118 | + } |
| 119 | + } else if (selector.nodeType) { |
| 120 | + this.context = this[0] = selector; |
| 121 | + this.length = 1; |
| 122 | + return this; |
| 123 | + } |
| 124 | + |
| 125 | + }, |
| 126 | + css: function() { |
| 127 | + console.log("di~~didi~~") |
| 128 | + }, |
| 129 | + //.... |
| 130 | + } |
| 131 | + |
| 132 | + jQuery.fn.init.prototype = jQuery.fn; |
| 133 | + |
| 134 | + |
| 135 | + jQuery.extend = jQuery.prototype.extend = function() { |
| 136 | + var target = arguments[0] || {}; |
| 137 | + var length = arguments.length; |
| 138 | + var i = 1; |
| 139 | + var deep = false; //默认为浅拷贝 |
| 140 | + var option; |
| 141 | + var name; |
| 142 | + var copy; |
| 143 | + var src; |
| 144 | + var copyIsArray; |
| 145 | + var clone; |
| 146 | + |
| 147 | + if (typeof target === "boolean") { |
| 148 | + deep = target; |
| 149 | + target = arguments[1]; |
| 150 | + i = 2; |
| 151 | + } |
| 152 | + |
| 153 | + if (typeof target !== "object") { |
| 154 | + target = {}; |
| 155 | + } |
| 156 | + |
| 157 | + if (length == i) { |
| 158 | + target = this; |
| 159 | + i--; //0 |
| 160 | + } |
| 161 | + |
| 162 | + for (; i < length; i++) { |
| 163 | + if ((option = arguments[i]) !== null) { |
| 164 | + for (name in option) { |
| 165 | + src = target[name]; |
| 166 | + copy = option[name]; |
| 167 | + if (deep && (jQuery.isPlainObject(copy) || (copyIsArray = jQuery.isArray(copy)))) { |
| 168 | + if (copyIsArray) { |
| 169 | + copyIsArray = false; |
| 170 | + clone = src && jQuery.isArray(src) ? src : []; |
| 171 | + } else { |
| 172 | + clone = src && jQuery.isPlainObject(src) ? src : {}; |
| 173 | + } |
| 174 | + target[name] = jQuery.extend(deep, clone, copy); |
| 175 | + } else if (copy !== undefined) { |
| 176 | + target[name] = copy; |
| 177 | + } |
| 178 | + } |
| 179 | + } |
| 180 | + } |
| 181 | + return target; |
| 182 | + } |
| 183 | + |
| 184 | + |
| 185 | + jQuery.extend({ |
| 186 | + //类型检测 |
| 187 | + isPlainObject: function(obj) { |
| 188 | + return typeof obj === "object"; |
| 189 | + }, |
| 190 | + |
| 191 | + isArray: function(obj) { |
| 192 | + return toString.call(obj) === "[object Array]"; |
| 193 | + }, |
| 194 | + |
| 195 | + isFunction: function(fn) { |
| 196 | + return toString.call(fn) === "[object Function]"; |
| 197 | + }, |
| 198 | + //类数组转化成正真的数组 |
| 199 | + markArray: function(arr, results) { |
| 200 | + var ret = results || []; |
| 201 | + if (arr != null) { |
| 202 | + jQuery.merge(ret, typeof arr === "string" ? [arr] : arr); |
| 203 | + } |
| 204 | + return ret; |
| 205 | + }, |
| 206 | + |
| 207 | + //合并数组 |
| 208 | + merge: function(first, second) { |
| 209 | + var l = second.length, |
| 210 | + i = first.length, |
| 211 | + j = 0; |
| 212 | + |
| 213 | + if (typeof l === "number") { |
| 214 | + for (; j < l; j++) { |
| 215 | + first[i++] = second[j]; |
| 216 | + } |
| 217 | + } else { |
| 218 | + while (second[j] !== undefined) { |
| 219 | + first[i++] = second[j++]; |
| 220 | + } |
| 221 | + } |
| 222 | + |
| 223 | + first.length = i; |
| 224 | + |
| 225 | + return first; |
| 226 | + }, |
| 227 | + |
| 228 | + parseHTML: function(data, context) { |
| 229 | + if (!data || typeof data !== "string") { |
| 230 | + return null; |
| 231 | + } |
| 232 | + //过滤掉<a> <a> => a |
| 233 | + var parse = rejectExp.exec(data); |
| 234 | + console.log(parse) |
| 235 | + return [context.createElement(parse[1])]; |
| 236 | + }, |
| 237 | + }); |
| 238 | + |
| 239 | + root.$ = root.jQuery = jQuery; |
| 240 | +})(this); |
| 241 | +```` |
| 242 | + |
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