1. When we use the $ symbol to call the method directly. How is it encapsulated inside jQuery? Are you curious?
// jQuery.extend 的方法 是绑定在 $ 上面的。 jQuery.extend( { //expando 用于决定当前页面的唯一性。 /\D/ 非数字。其实就是去掉小数点。 expando: "jQuery" + ( version + Math.random() ).replace( /\D/g, "" ), // Assume jQuery is ready without the ready module isReady: true, // 报错的情况 error: function( msg ) { throw new Error( msg ); }, // 空函数 noop: function() {}, // 判断是不是一个函数 isFunction: function( obj ) { return jQuery.type( obj ) === "function"; }, //判断当前对象是不是window对象。 isWindow: function( obj ) { return obj != null && obj === obj.window; }, //判断obj是不是一个数字 当为一个数字字符串的时候页可以的哦 比如 "3.2" isNumeric: function( obj ) { var type = jQuery.type( obj ); return ( type === "number" || type === "string" ) && // 这个话的意思就是要限制 "3afc 这个类型的 字符串" !isNaN( obj - parseFloat( obj ) ); }, //判断obj 是不是一个对象 isPlainObject: function( obj ) { var proto, Ctor; // obj 存在且 toString.call(obj) !== "[object object]"; 就肯定不是一个对象了。 if ( !obj || toString.call( obj ) !== "[object Object]" ) { return false; } //getProto获取原型链上的对象。 getProto = Object.getPrototypeOf(); 获取原型链上的属性 proto = getProto( obj ); // getProto(Object.create(null)) -> proto == null 这种情况也是对象 obj = Object.create(null); if ( !proto ) { return true; } // obj 原型上的属性。 proto 上面有 constructor hasOwn = hasOwnPrototypeOf('name') 判断某个对象自身是否有 这个属性 // Ctor: 当 proto 自身有constructor的时候, 取得constructor 这个属性的value 值。 其实就是 obj的构造函数。 type -> function Ctor = hasOwn.call( proto, "constructor" ) && proto.constructor; //Ctor 类型为“function” 且 为构造函数类型吧。 这个时候 obj 也是对象。 我的理解 这个时候,obj = new O(); 其实就是某个构造函数的实列 return typeof Ctor === "function" && fnToString.call( Ctor ) === ObjectFunctionString; }, //判断obj是不是一个空对象 isEmptyObject: function( obj ) { //var o = {} var name; for ( name in obj ) { return false; } return true; }, //获取js的数据类型。 其实方法就是 Object.prototype.toString.call(xx); xx 就是要检测的某个变量。 得到的结果是 "[object object]" "[object array]" ... type: function( obj ) { //除去null 和undefined 的情况。 返回本身。 也就是 null 或者 undefined. 因为 undefined == null -> true。 if ( obj == null ) { return obj + ""; } // 这个跟typeof xx(某个变量 ) -> undefined object,number,string,function,boolean(typeof 一个变量只能得到6中数据类型) /** * 1. obj 是一个对象 或者 obj 是一个 function 那么 直接class2type[toString.call(obj)] 这个话其实是在class2type 中根据key值找到对应的value。 * class2type = { * [object object]: "object", * [object array]:"array" ... * * } * 这样类似的值。 * class2type[toString.call(obj)] || "object" 连起来读就是,在class2type 中找不到类型的值,就直接返回 object * * 2.或者返回 typeof obj。的数据类型。 -> number, string,boolean 基本数据了类型吧。 (js 中有5中基本数据类型。 null ,undefined,number,string,boolean) */ return typeof obj === "object" || typeof obj === "function" ? class2type[ toString.call( obj ) ] || "object" : typeof obj; }, // 翻译为:全局的Eval函数。 说句实话。没有看懂这个是拿来干嘛的。 DOMval(); /** * * @param code * function DOMEval( code, doc ) { doc = doc || document; var script = doc.createElement( "script" ); script.text = code; doc.head.appendChild( script ).parentNode.removeChild( script ); } 创建一个 script标签, 或remove 这个标签。 目前没有搞懂拿来干嘛用。 */ globalEval: function( code ) { DOMEval( code ); }, // 这个是用来转为 驼峰的用函数吧。 ms- 前缀转为驼峰的吧。 camelCase: function( string ) { return string.replace( rmsPrefix, "ms-" ).replace( rdashAlpha, fcamelCase ); }, // each 方法。 $.each(obj,function(){}); 用于循环数组和对象的方法。 each: function( obj, callback ) { var length, i = 0; if ( isArrayLike( obj ) ) { // 当obj 是一个数组的时候执行这个方法 length = obj.length; for ( ; i < length; i++ ) { /*当$.each(obj,function(i,item){ if( i = 2){ return false。 } }) 当$.each(obj,function(){}) 中的匿名函数中纯在 return false; 的时候跳出循环。 */ if ( callback.call( obj[ i ], i, obj[ i ] ) === false ) { break; } } } else { // for in 循环对象。 callback.call(obj[i],i,obj,[i]) === false 跟数组循环是一道理 for ( i in obj ) { if ( callback.call( obj[ i ], i, obj[ i ] ) === false ) { break; } } } return obj; }, // 去掉 text 两边的空白字符 $("input").val().trim() 一个道理吧。 text + "" 其实是为了把 text 转成一个字符串。 类型这种情况 123.replace(rtrim,"") 是会报错的。 // 如果 123 + "" 其实变成了 "123" trim: function( text ) { return text == null ? "" : ( text + "" ).replace( rtrim, "" ); }, // $.makeArray 其实是将类数组转换成数组 对象。 /** * * * @param arr * @param results * @returns {*|Array} * 比如: var b = document.getElementsByTagName("p"); b.reverse() 。 用b 来调reserver() 方法会直接报错的。因为这个时候b是类数组对象。 * var a = $.makeArray(document.getElementsByTagName("p")); a.reverser()。 这样就不会报错了。 * */ makeArray: function( arr, results ) { var ret = results || []; if ( arr != null ) { if ( isArrayLike( Object( arr ) ) ) { jQuery.merge( ret, typeof arr === "string" ? [ arr ] : arr ); } else { push.call( ret, arr ); } } return ret; }, /** * * @param elem 要检测的值 * @param arr 待处理的数组 * @param i 从待处理的数组的第几位开始查询. 默认是0 * @returns {number} 返回 -1 。表示arr 中没有该value值, 或者该值的下表 * $.inArray()。 * */ inArray: function( elem, arr, i ) { //如果arr 为 null 直接返回 -1 。 /** * 对indxOf.call(arr,elem,i);方法的解释 * var s = new String(); * eg: var indexOf = s.indexOf; 用indexOf 变量来存字符串中的 indexOf的方法。 * indexOf.call(arr,elem,i) ; 其实就是把字符串的indexOf 继承给数组,并且传递 elem 和 i 参数。 * 更简单一点其实可以理解为: arr.indexOf(elem,i); */ return arr == null ? -1 : indexOf.call( arr, elem, i ); }, // 合并数组 /** * * @param first 第一个数组 * @param second 第二个数组 * @returns {*} */ merge: function( first, second ) { var len = +second.length, //第二个数组的长度 j = 0, //j 从0 开始 i = first.length; //第一个数组的长度 for ( ; j < len; j++ ) { first[ i++ ] = second[ j ]; } // 其实用push 应该可以吧。 first.length = i; return first; }, /** * * @param elems 带过滤的函数 * @param callback 过滤的添加函数 * @param invert 来决定 $.grep(arr,callback) 返回来的数组,是满足条件的还是不满足条件的。 true 是满足条件的。 false 是不满足条件的。 * @returns {Array} * * 返回一个数组。 */ grep: function( elems, callback, invert ) { var callbackInverse, matches = [], i = 0, length = elems.length, callbackExpect = !invert; // Go through the array, only saving the items // that pass the validator function for ( ; i < length; i++ ) { callbackInverse = !callback( elems[ i ], i ); if ( callbackInverse !== callbackExpect ) { matches.push( elems[ i ] ); } } return matches; }, /** * * @param elems 带处理的数组 * @param callback 回调函数 * @param arg 这参数用在callback回调函数的。 * callback(elems[i],i,arg) * @returns {*} * * $.map(arr,function(item,i,arg){},arg) * 将一个数组,通过callback 转换成另一个数组。 * eg: var b = [2,3,4]; * var a = $.map(b,function(item,i,arg){ * return item + arg; * },1) * console.log(a) [3,4,5] */ map: function( elems, callback, arg ) { var length, value, i = 0, ret = []; // Go through the array, translating each of the items to their new values if ( isArrayLike( elems ) ) { length = elems.length; for ( ; i < length; i++ ) { value = callback( elems[ i ], i, arg ); if ( value != null ) { ret.push( value ); } } // Go through every key on the object, } else { for ( i in elems ) { value = callback( elems[ i ], i, arg ); if ( value != null ) { ret.push( value ); } } } // Flatten any nested arrays return concat.apply( [], ret ); }, // 对对象的一个全局标志量吧。 没搞懂具体用处 guid: 1, // Bind a function to a context, optionally partially applying any // arguments. /** * * @param fn * @param context * @returns {*} * * es6也提供了 new Proxy() 。对象。 */ proxy: function( fn, context ) { var tmp, args, proxy; //当content是字符串的时候 if ( typeof context === "string" ) { tmp = fn[ context ]; context = fn; fn = tmp; } // Quick check to determine if target is callable, in the spec // this throws a TypeError, but we will just return undefined. if ( !jQuery.isFunction( fn ) ) { return undefined; } // Simulated bind args = slice.call( arguments, 2 ); proxy = function() { return fn.apply( context || this, args.concat( slice.call( arguments ) ) ); }; // Set the guid of unique handler to the same of original handler, so it can be removed proxy.guid = fn.guid = fn.guid || jQuery.guid++; return proxy; }, //$.now 当前时间搓 now: Date.now, // jQuery.support is not used in Core but other projects attach their // properties to it so it needs to exist. /** * 检测浏览器是否支持某个属性 * $.support.style */ support: support } );
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