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---
id: 587d7fae367417b2b2512be3
title: Get JSON with the JavaScript XMLHttpRequest Method
challengeType: 6
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forumTopicId: 301502
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dashedName: get-json-with-the-javascript-xmlhttprequest-method
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---
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# --description--
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You can also request data from an external source. This is where APIs come into play.
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Remember that APIs - or Application Programming Interfaces - are tools that computers use to communicate with one another. You'll learn how to update HTML with the data we get from APIs using a technology called AJAX.
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Most web APIs transfer data in a format called JSON. JSON stands for JavaScript Object Notation.
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JSON syntax looks very similar to JavaScript object literal notation. JSON has object properties and their current values, sandwiched between a `{` and a `}` .
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These properties and their values are often referred to as "key-value pairs".
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However, JSON transmitted by APIs are sent as `bytes` , and your application receives it as a `string` . These can be converted into JavaScript objects, but they are not JavaScript objects by default. The `JSON.parse` method parses the string and constructs the JavaScript object described by it.
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You can request the JSON from freeCodeCamp's Cat Photo API. Here's the code you can put in your click event to do this:
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```js
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const req = new XMLHttpRequest();
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req.open("GET",'/json/cats.json',true);
req.send();
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req.onload = function(){
const json = JSON.parse(req.responseText);
document.getElementsByClassName('message')[0].innerHTML = JSON.stringify(json);
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};
```
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Here's a review of what each piece is doing. The JavaScript `XMLHttpRequest` object has a number of properties and methods that are used to transfer data. First, an instance of the `XMLHttpRequest` object is created and saved in the `req` variable. Next, the `open` method initializes a request - this example is requesting data from an API, therefore is a `GET` request. The second argument for `open` is the URL of the API you are requesting data from. The third argument is a Boolean value where `true` makes it an asynchronous request. The `send` method sends the request. Finally, the `onload` event handler parses the returned data and applies the `JSON.stringify` method to convert the JavaScript object into a string. This string is then inserted as the message text.
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# --instructions--
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Update the code to create and send a `GET` request to the freeCodeCamp Cat Photo API. Then click the `Get Message` button. Your AJAX function will replace the `The message will go here` text with the raw JSON output from the API.
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# --hints--
Your code should create a new `XMLHttpRequest` .
```js
assert(code.match(/new\s+?XMLHttpRequest\(\s*?\)/g));
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```
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Your code should use the `open` method to initialize a `GET` request to the freeCodeCamp Cat Photo API.
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```js
assert(
code.match(
/\.open\(\s*?('|")GET\1\s*?,\s*?('|")\/json\/cats\.json\2\s*?,\s*?true\s*?\)/g
)
);
```
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Your code should use the `send` method to send the request.
```js
assert(code.match(/\.send\(\s*\)/g));
```
Your code should have an `onload` event handler set to a function.
```js
assert(
code.match(/\.onload\s*=\s*(function|\(\s*?\))\s*?(\(\s*?\)|\=\>)\s*?{/g)
);
```
Your code should use the `JSON.parse` method to parse the `responseText` .
```js
assert(code.match(/JSON\s*\.parse\(\s*.*\.responseText\s*\)/g));
```
Your code should get the element with class `message` and change its inner HTML to the string of JSON data.
```js
assert(
code.match(
/document\s*\.getElementsByClassName\(\s*?('|")message\1\s*?\)\[0\]\s*\.innerHTML\s*?=\s*?JSON\.stringify\(.+?\)/g
)
);
```
# --seed--
## --seed-contents--
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```html
< script >
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document.addEventListener('DOMContentLoaded', function(){
document.getElementById('getMessage').onclick = function(){
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// Add your code below this line
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// Add your code above this line
};
});
< / script >
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< style >
body {
text-align: center;
font-family: "Helvetica", sans-serif;
}
h1 {
font-size: 2em;
font-weight: bold;
}
.box {
border-radius: 5px;
background-color: #eee ;
padding: 20px 5px;
}
button {
color: white;
background-color: #4791d0 ;
border-radius: 5px;
border: 1px solid #4791d0 ;
padding: 5px 10px 8px 10px;
}
button:hover {
background-color: #0F5897 ;
border: 1px solid #0F5897 ;
}
< / style >
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< h1 > Cat Photo Finder< / h1 >
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< p class = "message box" >
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The message will go here
< / p >
< p >
< button id = "getMessage" >
Get Message
< / button >
< / p >
```
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# --solutions--
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```html
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< script >
document.addEventListener('DOMContentLoaded',function(){
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document.getElementById('getMessage').onclick = function(){
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const req = new XMLHttpRequest();
req.open('GET', '/json/cats.json', true);
req.send();
req.onload = () => {
const json = JSON.parse(req.responseText);
document.getElementsByClassName('message')[0].innerHTML = JSON.stringify(json);
};
};
});
< / script >
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< style >
body {
text-align: center;
font-family: "Helvetica", sans-serif;
}
h1 {
font-size: 2em;
font-weight: bold;
}
.box {
border-radius: 5px;
background-color: #eee ;
padding: 20px 5px;
}
button {
color: white;
background-color: #4791d0 ;
border-radius: 5px;
border: 1px solid #4791d0 ;
padding: 5px 10px 8px 10px;
}
button:hover {
background-color: #0F5897 ;
border: 1px solid #0F5897 ;
}
< / style >
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< h1 > Cat Photo Finder< / h1 >
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< p class = "message box" >
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The message will go here
< / p >
< p >
< button id = "getMessage" >
Get Message
< / button >
< / p >
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```