169 lines
4.4 KiB
Markdown
169 lines
4.4 KiB
Markdown
---
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id: 5ccfad82bb2dc6c965a848e5
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title: Get JSON with the JavaScript fetch method
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challengeType: 6
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forumTopicId: 301501
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---
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## Description
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<section id='description'>
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Another way to request external data is to use the JavaScript <code>fetch()</code> method. It is equivalent to XMLHttpRequest, but the syntax is considered easier to understand.
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Here is the code for making a GET request to <code>/json/cats.json</code>
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```js
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fetch('/json/cats.json')
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.then(response => response.json())
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.then(data => {
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document.getElementById('message').innerHTML = JSON.stringify(data);
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})
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```
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Take a look at each piece of this code.
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The first line is the one that makes the request. So, <code>fetch(URL)</code> makes a GET request to the URL specified. The method returns a Promise.
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After a Promise is returned, if the request was successful, the <code>then</code> method is executed, which takes the response and converts it to JSON format.
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The <code>then</code> method also returns a Promise, which is handled by the next <code>then</code> method. The argument in the second <code>then</code> is the JSON object you are looking for!
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Now, it selects the element that will receive the data by using <code>document.getElementById()</code>. Then it modifies the HTML code of the element by inserting a string created from the JSON object returned from the request.
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</section>
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## Instructions
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<section id='instructions'>
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Update the code to create and send a "GET" request to the freeCodeCamp Cat Photo API. But this time, using the <code>fetch</code> method instead of <code>XMLHttpRequest</code>.
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</section>
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## Tests
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<section id='tests'>
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```yml
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tests:
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- text: Your code should make a GET request with <code>fetch</code>.
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testString: assert(code.match(/fetch\s*\(\s*('|")\/json\/cats\.json\1\s*\)/g));
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- text: Your code should use <code>then</code> to convert the response to JSON.
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testString: assert(code.match(/\.then\s*\(\s*(response|\(\s*response\s*\))\s*=>\s*response\s*\.json\s*\(\s*\)\s*\)/g))
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- text: Your code should use <code>then</code> to handle the data converted to JSON by the other <code>then</code>.
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testString: assert(code.match(/\.then\s*\(\s*(data|\(\s*data\s*\))\s*=>\s*{[^}]*}\s*\)/g))
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- text: Your code should get the element with id <code>message</code> and change its inner HTML to the string of JSON data.
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testString: assert(code.match(/document\s*\.getElementById\s*\(\s*('|")message\1\s*\)\s*\.innerHTML\s*=\s*JSON\s*\.\s*stringify\s*\(\s*data\s*\)/g));
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```
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</section>
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## Challenge Seed
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<section id='challengeSeed'>
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<div id='html-seed'>
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```html
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<script>
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document.addEventListener('DOMContentLoaded',function(){
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document.getElementById('getMessage').onclick= () => {
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// Add your code below this line
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// Add your code above this line
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};
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});
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</script>
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<style>
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body {
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text-align: center;
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font-family: "Helvetica", sans-serif;
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}
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h1 {
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font-size: 2em;
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font-weight: bold;
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}
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.box {
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border-radius: 5px;
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background-color: #eee;
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padding: 20px 5px;
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}
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button {
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color: white;
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background-color: #4791d0;
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border-radius: 5px;
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border: 1px solid #4791d0;
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padding: 5px 10px 8px 10px;
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}
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button:hover {
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background-color: #0F5897;
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border: 1px solid #0F5897;
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}
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</style>
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<h1>Cat Photo Finder</h1>
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<p id="message" class="box">
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The message will go here
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</p>
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<p>
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<button id="getMessage">
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Get Message
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</button>
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</p>
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```
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</div>
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</section>
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## Solution
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<section id='solution'>
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```html
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<script>
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document.addEventListener('DOMContentLoaded',function(){
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document.getElementById('getMessage').onclick= () => {
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fetch('/json/cats.json')
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.then(response => response.json())
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.then(data => {
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document.getElementById('message').innerHTML=JSON.stringify(data);
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})
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};
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});
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</script>
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<style>
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body {
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text-align: center;
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font-family: "Helvetica", sans-serif;
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}
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h1 {
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font-size: 2em;
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font-weight: bold;
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}
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.box {
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border-radius: 5px;
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background-color: #eee;
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padding: 20px 5px;
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}
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button {
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color: white;
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background-color: #4791d0;
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border-radius: 5px;
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border: 1px solid #4791d0;
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padding: 5px 10px 8px 10px;
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}
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button:hover {
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background-color: #0F5897;
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border: 1px solid #0F5897;
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}
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</style>
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<h1>Cat Photo Finder</h1>
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<p id="message" class="box">
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The message will go here
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</p>
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<p>
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<button id="getMessage">
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Get Message
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</button>
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</p>
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```
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</section>
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