JavaScript Code

The JavaScript Code step allows you to write JavaScript code that will run when the step is executed with the Async/Await syntax support. Among the most common use cases for this action step are data mapping and transforming, validation, and preparing data before sending it to a database/API.

You can use the UI Bakery {{data}} variable to access the result of the previous step or {{ui.input.value}} to access the value of a specific UI component.

Additionally, you can also use the JS libraries included in UI Bakery as well as connect custom ones to utilize their functionality within your code. Learn more about them 👇

Using JS libraries

Variables

Built-in variables

// result of the previous step
return {{data}};

// error response of the previous step
return {{error}};

// incoming action params, passed in by components,
// the Execution/Loop action steps or when calling the action from the code
return {{params}};

// the response of the request, if the Code step follows an HTTP API step
return {{res}};

While {{data}} and {{error}} are specific to a particular step, {{params}} is available in all steps.

Using variables

// use `{{data.<key>}}` to access a specific key
return {{data.name}};

// to access the first element of the array
return {{data[0]}};

// to access the `name` key of the first element
return {{data[0].name}};

Optional chaining and default values

If at some point a variable's value is null or undefined, an optional chaining operator ?. can be used to access a specific key, for example:

// if `data` is `null` or `undefined`, `name` will not produce an error
return {{data?.name}};
// if `data` is `null` or `undefined`, `name` will not produce an error
return {{data?.[0]?.name}};

If a variable is null or undefined, a default value can be provided using the nullish coalescing operator ??:

// the default value will be returned
return {{data?.name ?? 'default'}};

It can also be used in combination with the if statement:

const userRole = {{data?.role ?? 'user'}};
if (userRole === 'admin') {
  // do something
}

Using variables inside strings

If you need to add a variable inside a string, you can do it by placing it in the ${ } expression, for example:

const name = `Hello ${ {{user.name}} }`;

Data transformation

If the API returns its data in a different format than expected for the components, you can use the JavaScript Code step to transform it. For example, a Table component expects an array of objects but the API returns an object with the items key that contains the array. In this case, you can use the following code to transform it into the desired format:

return {{data.items}};

In some cases, the API may return an object with the data key inside:

return {{data.data}};

• Access an inner array object and map it to a new array:

return {{data}}.map(item => {
  return {
    id: item.id,
    name: item.name.toUpperCase(),
  };
});

• Add a new key to the array of objects:

return {{data}}.map(item => {
  return {
    ...item, // put all the keys from the original object
    created_at: new Date(), // add a new property
  };
});

• Filter an array of objects (short version):

return {{data}}.filter(item => item.id > 10);

Multiline version:

return {{data}}.filter((item) => {
  return item.id > 10;
});

Component values & methods

In the JavaScript Code step, you can access the values of UI components and call their methods. For example, if you have a Form component, you can access its value using the {{ui.form.value}} variable.

const formValue = {{ui.form.value}};
delete formValue.password;

return formValue;

You can also call component methods, for example, {{ui.form.submit()}} will submit the form.

// ui.form.submit() can also be used without the parentheses
{{ui.form.submit()}}

Another example is hiding the modal - you can use the {{ui.modal.close()}} method:

// ui.modal.close() can also be used without the parentheses
{{ui.modal.close()}}

Merging data

Merging results of multiple steps

In some cases, you may need to merge the results of multiple steps into a single object. Here, you can use {{steps.<step_name>.data}} to access the output of any previous step:

const users = {{steps.loadUsers.data}};
const orders = {{steps.loadOrders.data}};

return users.map(user => {
  const userOrders = orders
    .filter(order => order.userId === user.id);

  return {
    ...user,
    userOrders,
  };
});

Some steps, such as Save to State or Show Notification, do not have a variable as they do not produce any output.

Action step must have a name to be accessible as a variable.

Calling and merging data from other actions

Sometimes, you may need to call another action to get some data and then merge it with your current data. For example, you have a list of users, and you want to get a list of their orders. You can use the following code to call another action and merge its result with your current data:

const orders = await {{actions.loadOrders.trigger()}};

// Note that the `async` keyword is required
return {{data}}.map(async (item) => {
  return {
    ...item,
    // user id will be passed as a {{params}} to the action
    orders: await {{actions.loadOrders.trigger(item.id)}},
};
});

Another example is loading two different lists of data and merge them into one array:

const users = await {{actions.loadUsers.trigger()}};
const orders = await {{actions.loadOrders.trigger()}};

return {{users}}.map(item => {
  return {
    ...item,
    orders: orders.filter(order => order.user_id === item.id),
  };
});

Custom validation

If you need to validate the data before submitting it to a database or an API, you can simply throw an error with a custom message:

if (!{{data.name}}) {
  throw new Error('User name is a required field');
}

This will prevent the action from executing the next steps.

Alternatively, you can also select the Allow next step execution when this step has failed checkbox in the action's settings and use the message in the Show Notification step as the {{error.message}}.

Debugging errors

If the code fails or produces unexpected results you can try doing the following:

• Make sure no linter errors are present in the code (for example, an exclamation mark in the left gutter).

• Check the result of the previous step (the {{data}} variable) and other variables (for example, {{params}}).

• Comment out the code and add return {{data}}; - to check if the data is in the expected format.

• Use the console.log to print the data to the console (the action's Logs tab):

// commented to test
// if ({{data}}.length > 10) {
//   return {{data}};
// }

console.log({{data}});

Useful examples

Map data for the select component

return {{data}}.map(item => {
  return {
    label: item.name,
    value: item.id,
  };
});

Add a "Not Selected" option at the beginning of the array

const items = {{data}}.map(item => {
  return {
    label: item.name,
    value: item.id,
  };
});

items.unshift({ value: null, label: 'Not Selected' });

return items;

Add color to the Select dropdown items

const colors = ['success', 'warning', 'danger', 'info', 'basic', 'control', 'primary'];
const items = {{data}}.map((item, index) => {
  const color = colors[index] ? colors[index] : 0;
  return { value: item.productLine, label: item.productLine, color };
});

items.unshift({ value: null, label: 'Not Selected' });
return items;

Refresh action data at a certain interval

Create an action, select the JavaScript Code action step and add the following code:

const { interval } = await requireAsync('rxjs');
// internal is specified in miliseconds
return interval(5000);

For the second step in this action, add the Load Table action or any other load data step.

Safely parse JSON result into a variable

const items = {};
try {
  items = JSON.parse(data['items']);
} catch (e) {}

return items;