API 留言板練習-Part 2 : 前端串 API


Posted by tzutzu858 on 2020-11-02

因為是跨網域存取 API,所以 API 都要記得加上 header('Access-Control-Allow-Origin: *');

先打造 UI ,有用到 bootstrap 和 jquery
index.html

<!DOCTYPE html>
<html>

<head>
  <meta charset="utf-8">
  <title>留言板</title>
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <script src="https://code.jquery.com/jquery-3.5.1.min.js"></script>
  <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@4.5.3/dist/css/bootstrap.min.css"
    integrity="sha384-TX8t27EcRE3e/ihU7zmQxVncDAy5uIKz4rEkgIXeMed4M0jlfIDPvg6uqKI2xXr2" crossorigin="anonymous">
  <style>
    .card {
      margin-top: 12px;
    }
  </style>
</head>

<body>
  <div class="container">
    <form class="add-comment-form">
      <div class="form-group">
        <label for="form-nickname">暱稱</label>
        <input name="nickname" type="text" class="form-control" id="exampleInputEmail1">
      </div>
      <div class="form-group">
        <label for="content-textarea">留言內容</label>
        <textarea name='content' class="form-control" id="exampleFormControlTextarea1" rows="3"></textarea>
      </div>
      <button type="submit" class="btn btn-primary">送出</button>
    </form>
    <div class="comments">
    </div>
  </div>
</body>

</html>

出來圖案長這樣


js 部分

拿 API

$(document).ready(() => {
    $.ajax({
        url: 'http://localhost/hw1_12/api_comments.php?site_key=tzu',
    }).done(function (data) {
        if (!data.ok) {
            alert(data.message)
            return
        }
    });
})

用迴圈顯現出來,資料要用 escape() 防 XSS

const comments = data.discussions;
for (let comment of comments) {
    $('.comments').append(`
        <div class="card">
            <div class="card-body">
                <div class="d-flex justify-content-between">
                    <h5 class="card-title">${escape(comment.nickname)}</h5>
                    <p>${comment.created_at}</p>
                </div>
                <p class="card-text">${escape(comment.content)}</p>
            </div>
        </div>
    `)
}

function escape(toOutput) {
    return toOutput.replace(/\&/g, '&amp;')
        .replace(/\</g, '&lt;')
        .replace(/\>/g, '&gt;')
        .replace(/\"/g, '&quot;')
        .replace(/\'/g, '&#x27')
        .replace(/\//g, '&#x2F');
}

post 資料到後端

監聽表單,先阻止預設行為 e.preventDefault(); ,用 POST 傳 site_key、nickname、content 到 API

$('.add-comment-form').submit(e => {
    e.preventDefault();
    $.ajax({
        type: 'POST',
        url: 'http://localhost/hw1_12/api_add_comments.php',
        data: {
            site_key: 'tzu',
            nickname: $('input[name=nickname]').val(),
            content: $('textarea[name=content]').val()
        }
    }).done(function (data) {
        if (!data.ok) {
            alert(data.message)
            return
        }
    });
})

傳到後端成功之後,有幾種作法,直接把剛剛新增成功的留言內容放上去,另外一種就是再 query 一次 API,把 API 裡面新的內容放上去,先把原本新增的內容用一個 function 包起來

function appendCommentToDOM(container, comment) {
    const html = `
    <div class="card">
        <div class="card-body">
            <div class="d-flex justify-content-between">
                <h5 class="card-title">${escape(comment.nickname)}</h5>
                <p>${comment.created_at}</p>
            </div>
        <p class="card-text">${escape(comment.content)}</p>
        </div>
    </div>
        `
    container.append(html)
}

這樣顯示時,只要把參數傳進去就好

const commentDOM = $('.comments')
const comments = data.discussions;
for (let comment of comments) {
   appendCommentToDOM(commentDOM, comment)
}

回到之前資料傳到後端成功之後,在要做的事情就可以一樣放 appendCommentToDOM 這個 function 就好

const commentsDOM = $('.comments')

const newCommentData = {
      site_key: 'tzu',
      nickname: $('input[name=nickname]').val(),
      content: $('textarea[name=content]').val()
}

appendCommentToDOM(commentsDOM, newCommentData)

成功之後傳個空字串清空值

$('input[name=nickname]').val('')
$('textarea[name=content]').val('')









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