版块

• 香草Javascript🌿

  原生的Javascript是学好其他Javascript库的基础

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  Promise (承诺) 函数用于实现callback的功能，即在一个函数结束后调用另外一个函数。 比如下面这个例子： function do_thing1(){ setTimeout( function(){ console.log( 'do thing1' ); }, 1000 ); } function do_thing2(){ console.log( 'do thing2' ); } do_thing1(); do_thing2(); 这里我们先调用do_thing1因为我们希望do_thing2在 do_thing1结束后再执行，但是do_thing2没有等！ 我们可以用传统的callback来解决这个问题如下： function do_thing1(callback){ setTimeout( function(){ console.log( 'do thing1' ); callback && callback() }, 1000 ); } function do_thing2(){ console.log( 'do thing2' ); } do_thing1(do_thing2); 我把do_thing2当做一个变量传给do_thing1，等do_thing1结束后来调用do_thing2。 接下来，我们用Promise来解决这个问题： const do_thing1b = new Promise((resolve, reject) => setTimeout(() => { console.log("do_thing1b"); resolve("done"); }, 1000) ); const do_thing2b = () => { console.log("do thing2b"); }; do_thing1b.then(() => do_thing2b()); 因为do_thing1b现在是个Promise，所以我们可以用then来串接其他函数，即do_thing2，这样就确保do_thing2b一定在do_thing1b结束后才被调用。这就"承诺"!
• React

  React生于2011某月某日，开源于2013年五月29日，从此改变了前端世界！

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  const allPubs = rows.reduce((ac, item) => { const idx = ac.findIndex((x) => x.publicationName === item.publicationName); console.log("IDX", idx); if (idx === -1) { ac.push(item); } else { ac[idx].publicationQty += item.publicationQty; } return ac; }, []); const sortedRows = orderBy(allPubs, ["publicationQty"], ["desc"]);
• 笔记

  好记性不让烂笔头

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  In a package.json file, PeerDependencies are used to specify any packages that the current package requires to function properly, but should not be bundled with the package during installation. Instead, the PeerDependencies will be installed as a separate dependency of the consuming package, ensuring that only one version of the package is installed across all dependencies that require it. This helps to reduce duplication of code and potential conflicts between different versions of the same package. PeerDependencies are typically used for packages that provide interfaces or APIs that other packages need to use, such as plugins or libraries. Yes, it can be difficult to ensure that only one version of a package is installed across all dependencies that require it, especially if multiple packages have different version requirements for the same PeerDependency. However, by using PeerDependencies in combination with careful management of package versions and updating dependencies regularly, it is possible to minimize the risk of conflicts and ensure that the required packages are installed correctly. Some best practices for managing PeerDependencies include: Clearly defining the required versions of PeerDependencies in the package.json file Keeping all dependencies up to date to minimize version conflicts Testing the package with all required PeerDependencies to ensure compatibility Documenting the required PeerDependencies for users of the package Overall, while it may not always be straightforward to manage PeerDependencies, they can be a valuable tool for ensuring that packages function properly and that dependencies are installed efficiently.
• 重要通知

  社区大事看这里

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  据说中国发布的《大国战疫》一书由于某种原因下架了。如今新冠状病毒传播到世界各地，目前(3/12/2020)美国的确诊病例已经超过一千五百例！美国是超级大国，我们看看美国版大国战疫！
• 评论和反馈

  这里欢迎任何问题，包括需要开通新Fun板块

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• FUN版

  J4Fun的过去

  摄影Fun

  英语Fun
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  Please obtain a letter from her employer showing the dates her employment and benefits will end
• PHP
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  先发个牢骚：安装这些dependencies真是蛋疼啊！NPM rocks! 问题很多，今天先谈谈intl这个module吧。 brew install icu4c sudo pecl update-channels sudo pecl install intl 上面的第三个命令failed了，说是找不到icu。 折腾了很久，没搞定 - 睡觉 zzzzzzzz 早上，不小心run了 php -m | grep intl 返回结果intl也就是说已经安装了。但是phpinfo(),没有。很快意识到Apache没有指向正确的php。 In /etc/apache2/httpd.conf, #LoadModule php7_module libexec/apache2/libphp7.so LoadModule php7_module /usr/local/opt/php@7.4/lib/httpd/modules/libphp7.so sudo apacheclt restart 搞定了。 但是还是没明白，问什么sudo pecl install intl没成，还有intl是不是php7.4.5自带的呀？