I have been working on the mobile terminal recently. Since I am familiar with jQuery and Zepto provides the same API as jQuery, I chose Zepto as the development framework.
Since it is a mobile development, some new ES5 APIs are also used, such as forEach. Here are some examples of the code I wrote:
list.forEach(function(v) { return !!v; })
I naively thought that forEach was just like jQuery’s each. As long as my return value was false, it would interrupt the loop. So, I wrote a lot of traversal code like this (I was really too lazy to write it for each traversal). Declare variables)
After writing for a while, I suddenly discovered that the callback function of forEach cannot interrupt the loop, so I hung a function on Array.prototype, and then replacedAll, perfect.
Array.prototype.foreach = function(fn) { var i = 0, len = this.length; for (; i < len; ++i) { if (fn(this[i], i) === false) { break; } } };
Until one day, I wanted to do some optimization. Considering that the json that the client needs to save is too large (I kid you not, the maximum can be 20M), stringify is too time-consuming and will block the UI, so I Use Worker to open a thread in the background specifically to stringify this json, similar to this:
addEventListener("message", function(e) {
var data = e.data;
data = JSON.stringify(data);
postMessage(data);
}, false);
posMesage:
worker.postMessage(data)
But the console output the following error message:
Uncaught DataCloneError: Failed to execute 'postMessage' on 'Worker': An object could not be cloned.
What the hell, why can’t I even copy a json? So, I started looking for the reason, and I found this thing in my json:
Oh my god, what the hell is this? Why did this foreach come in? I looked at $.extend(true, {}, obj) in the editor and it was trembling there. I couldn’t help but wonder, it couldn’t be you. You must be causing trouble. So, I checked the source code of $.extend:
function extend(target, source, deep) { for (key in source) if (deep && (isPlainObject(source[key]) || isArray(source[key]))) { if (isPlainObject(source[key]) && !isPlainObject(target[key])) target[key] = {} if (isArray(source[key]) && !isArray(target[key])) target[key] = [] extend(target[key], source[key], deep) } else if (source[key] !== undefined) target[key] = source[key] } // Copy all but undefined properties from one or more // objects to the `target` object. $.extend = function(target){ var deep, args = slice.call(arguments, 1) if (typeof target == 'boolean') { deep = target target = args.shift() } args.forEach(function(arg){ extend(target, arg, deep) }) return target }
Oh my God, this guy is really causing trouble. It’s okay to use for...in... to traverse the array, but else if (source[key] !== undefined) target[key] = source[ key] Can the conditions here be more serious? Adding hasOwnProperty to check will not waste much time. With tears streaming down my face
After being cheated by Zepto, I immediately went to jQuery to complain, hoping it could comfort me, but unexpectedly:
jQuery.extend = jQuery.fn.extend = function() { var options, name, src, copy, copyIsArray, clone, target = arguments[0] || {}, i = 1, length = arguments.length, deep = false; // Handle a deep copy situation if ( typeof target === "boolean" ) { deep = target; target = arguments[1] || {}; // skip the boolean and the target i = 2; } // Handle case when target is a string or something (possible in deep copy) if ( typeof target !== "object" && !jQuery.isFunction(target) ) { target = {}; } // extend jQuery itself if only one argument is passed if ( length === i ) { target = this; --i; } for ( ; i < length; i++ ) { // Only deal with non-null/undefined values if ( (options = arguments[ i ]) != null ) { // Extend the base object for ( name in options ) { src = target[ name ]; copy = options[ name ]; // Prevent never-ending loop if ( target === copy ) { continue; } // Recurse if we're merging plain objects or arrays if ( deep && copy && ( jQuery.isPlainObject(copy) || (copyIsArray = jQuery.isArray(copy)) ) ) { if ( copyIsArray ) { copyIsArray = false; clone = src && jQuery.isArray(src) ? src : []; } else { clone = src && jQuery.isPlainObject(src) ? src : {}; } // Never move original objects, clone them target[ name ] = jQuery.extend( deep, clone, copy ); // Don't bring in undefined values } else if ( copy !== undefined ) { target[ name ] = copy; } } } } // Return the modified object return target; };
This guy is also else if ( copy !== undefined ) {target[ name ] = copy;} Just tell me, my dear mother.
In the end I had no choice but to write one myself.
Summary: When you want to use $.extend, don’t easily add your custom properties and methods to Array.prototype and Object.prototype, otherwise, you may have to find bugs in the future.
The above is the entire content of this article, I hope you all like it.

实现方法:1、用“$("img").delay(毫秒数).fadeOut()”语句,delay()设置延迟秒数;2、用“setTimeout(function(){ $("img").hide(); },毫秒值);”语句,通过定时器来延迟。

修改方法:1、用css()设置新样式,语法“$(元素).css("min-height","新值")”;2、用attr(),通过设置style属性来添加新样式,语法“$(元素).attr("style","min-height:新值")”。

区别:1、axios是一个异步请求框架,用于封装底层的XMLHttpRequest,而jquery是一个JavaScript库,只是顺便封装了dom操作;2、axios是基于承诺对象的,可以用承诺对象中的方法,而jquery不基于承诺对象。

增加元素的方法:1、用append(),语法“$("body").append(新元素)”,可向body内部的末尾处增加元素;2、用prepend(),语法“$("body").prepend(新元素)”,可向body内部的开始处增加元素。

在jquery中,apply()方法用于改变this指向,使用另一个对象替换当前对象,是应用某一对象的一个方法,语法为“apply(thisobj,[argarray])”;参数argarray表示的是以数组的形式进行传递。

删除方法:1、用empty(),语法“$("div").empty();”,可删除所有子节点和内容;2、用children()和remove(),语法“$("div").children().remove();”,只删除子元素,不删除内容。

on()方法有4个参数:1、第一个参数不可省略,规定要从被选元素添加的一个或多个事件或命名空间;2、第二个参数可省略,规定元素的事件处理程序;3、第三个参数可省略,规定传递到函数的额外数据;4、第四个参数可省略,规定当事件发生时运行的函数。

去掉方法:1、用“$(selector).removeAttr("readonly")”语句删除readonly属性;2、用“$(selector).attr("readonly",false)”将readonly属性的值设置为false。


Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

MinGW - Minimalist GNU for Windows
This project is in the process of being migrated to osdn.net/projects/mingw, you can continue to follow us there. MinGW: A native Windows port of the GNU Compiler Collection (GCC), freely distributable import libraries and header files for building native Windows applications; includes extensions to the MSVC runtime to support C99 functionality. All MinGW software can run on 64-bit Windows platforms.

DVWA
Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software

SecLists
SecLists is the ultimate security tester's companion. It is a collection of various types of lists that are frequently used during security assessments, all in one place. SecLists helps make security testing more efficient and productive by conveniently providing all the lists a security tester might need. List types include usernames, passwords, URLs, fuzzing payloads, sensitive data patterns, web shells, and more. The tester can simply pull this repository onto a new test machine and he will have access to every type of list he needs.

WebStorm Mac version
Useful JavaScript development tools

SublimeText3 Linux new version
SublimeText3 Linux latest version
