我最近在React.js中编写组件.我从来没有使用像componentWillMount和的方法componentDidMount.
render是不可或缺的. getInitialState我写的其他辅助方法也派上用场了.但不是前面提到的两种生命周期方法.
我目前的猜测是它们用于调试？我可以在其中调用console.log:
componentWillMount: function() {
console.log('component currently mounting');
},
componentDidMount: function() {
console.log('component has mounted');
}
还有其他用途吗？
比方说,例如,Fibonacci系列的迭代和递归版本.他们有相同的时间复杂性吗？
我正在尝试实现一个Read More链接，该链接会在单击后展开以显示更多文本。我正在尝试以 React 方式执行此操作。
<!--html-->
<div class="initialText">
Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book.
<a>
Read More
</a>
</div>
<div class="fullText">
Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text …我正在尝试设置模板，由此基于环境变量来指示我们是在开发、登台还是生产环境中，呈现的 HTML 指向不同的服务器。
为此，我想使用 Node 在 NODE_ENV 环境变量中所做的事情，然后根据我的代码有条件地设置路径。
if(process.env.NODE_ENV === 'development') {
/* development code */
} else {
/* production code */
}
Golang 有定义环境的标准吗？这看起来是一种合乎逻辑的方法吗？
我正在尝试为通过 ping Mailgun API 发送电子邮件的快速中间件函数编写单元测试。
module.exports = {
sendEmail: function (req, res) {
let reqBody = req.body;
let to = reqBody.to;
let from = reqBody.from;
let subject = reqBody.subject;
let emailBody = reqBody.body;
let data = {
from: from,
to: to,
subject: subject,
text: emailBody
};
mailgun.messages().send(data, function (error, body) {
if (error) {
res.status(400).json(error);
return;
}
res.status(200).json(body);
});
}
};
测试文件：
describe('\'sendEmail\' method', () => {
let mailgun;
beforeEach(() => {
mailgun = require('mailgun-js')({ apiKey: MAIL_GUN_API_KEY, domain: MAIL_GUN_DOMAIN }); …这是我得到的错误:
test.c:110:21: error: expected expression
else if(isupper(p_i))
^
1 error generated.
在else if代码结尾的声明中else if(isupper(p_i))- " " - 生成错误.
我在上面评论了这个'else if'声明.请让我知道什么是错的.谢谢.
#include <stdlib.h> // The library which contains the 'atoi()' function
#include <stdio.h> //
#include <cs50.h> // typedef char *string; and GetString()
#include <string.h> //
// 'argv[]' is an array of strings. (Fun fact: A string is an array of characters.)
// 'argc' is the integer variable which stores the number of strings that are in 'argv[]'. …