# JavaScript
Moropo uses Maestro's GraalJS engine to execute JavaScript steps inside your tests.
This provides a similar JavaScript environment to NodeJS.
**Note: it's not currently possible to import node\_modules**
### Creating a script
Add or upload a script directly from the Test Editor
### **Execute a script**
Use the [runScript command ](https://docs.moropo.com/creating-tests/commands/runflow-1)to call a script during a test run.
### Using Variables
`output` is a special JavaScript object which is shared by each test run and can be used to store variables for use in your tests.
For example, I could set `output.name` inside my JavaScript file called **get name**:
```javascript
output.name = 'billy'
```
In my test, I can then access this by calling `runScript` and then using `${}` to access the variable.
For example:
{% hint style="warning" %}
**IMPORTANT NOTE**\
Moropo does not currently persist JavaScript data between 'plays' in the Test Editor\
If a step requires a data set by JS, you must also select the dependent step when playing that step.
For example, in the below case step 3 requires a variable set by step 2. Every time I wish to play step 3, I must also select step 2.
{% endhint %}
## Making HTTP Requests
You can make HTTP requests using the built-in library.
For example, to make a simple GET request, filter the data, and save it to a variable:
```
const response = http.get("https://jsonplaceholder.typicode.com/users");
output.name = json(response.body).find(user => user.id === 2).name
```
### HTTP request methods
* `http.get("https://myendpoint.com")`
* `http.post("https://myendpoint.com")`
* `http.put("https://myendpoint.com")`
* `http.delete("https://myendpoint.com")`
### Headers
Headers can be passed using the `headers` parameter
```javascript
const response = http.get('https://myendpoint.com', {
headers: {
Authorization: 'Bearer myToken'
}
})
```
### JSON parsing
Use the `json()` built-in helper function to parse JSON responses.
```javascript
const response = http.get("https://jsonplaceholder.typicode.com/users");
const users = json(response.body);
// users = [
// { id: 1, name: "Clive" },
// { id: 2, name: "Barbie" }
// ]
output.name = users.find(user => user.id === 2).name;
// output.name = Barbie
```
