Frontend reference

Label Studio frontend (LSF) includes several UI options and callbacks that you can use when implementing the frontend with a custom labeling backend, or when customizing the Label Studio interface.

Updates to LSF in version 1.0.0

If you use LSF with a custom backend, you must make changes to the API callbacks that you use as follows:

If you rely on specific formatting of Label Studio completed tasks, Label Studio’s annotation format has also been updated.

Implement the Label Studio Frontend

var labelStudio = new LabelStudio("editor", options);

The following options are recognized when initializing a Label Studio instance version 1.0.0.

Options

config

Default: null

Type data: string

XML-based configuration of the labeling interface. This configuration relies on the data field of the task. See Customizable Tags for more information.

interfaces

Default: null

Type data: array

Collection of UI elements to show. Available interfaces:

• panel - Enable navigaion panel for the current task with buttons: undo, redo and reset.
• update - Show a button to update the current task after submitting.
• submit - Show a button to submit or update the current annotation.
• skip - Show a button to skip the current task.
• controls - Enable panel with controls (submit, update, skip).
• infobar - A show button for information.
• topbar - A labeling interface that lists the top-level items in the Label Studio UI.
• instruction - A button for the instructions.
• side-column - Show a column on the left or right side of the Label Studio UI.
• annotations:history - A show button for annotation history.
• annotations:tabs - A show button for annotation tabs.
• annotations:menu - A show button for the annotation menu.
• annotations:current - A show button for the current annotation.
• annotations:add-new - A show button to add new annotations.
• annotations:delete - A show button to delete the current annotation.
• annotations:view-all - A show button to view all annotations.
• predictions:tabs - Show predictions tabs.
• predictions:menu - Show predictions menu.
• auto-annotation - Show auto annotations.
• edit-history - Show edit history.

messages

Default: null

Type data: object

Messaging used for different actions

{
  DONE: "Done!",
  NO_COMP_LEFT: "No more annotations",
  NO_NEXT_TASK: "No more data available for labeling",
  NO_ACCESS: "You don't have access to this task"
}

• DONE - Shown after the task is submitted to the server
• NO_COMP_LEFT - Shown if there are no more annotations
• NO_NEXT_TASK - No next task to load
• NO_ACCESS - Can’t access the provided task

description

Default: No description

Type data: string

Description of the current task.

task

Task data

Default: null

Type data: object

{
  id: 1,
  load: false
  },
  data: {
    text: "Labeling text..."
  },
  annotations: [],
  predictions: [],
}

id

Type data: integer

Default: null

data

annotations

Type data: array

Array of annotations. See the annotation documentation for more information.

predictions

Type data: array

Array of predictions. Similar structure as completions or annotations. See the annotation documentation and guidance for importing predicted labels for more information.

user

User data

Type data: object

{
  "pk": 1,
  "firstName": "Stanley",
  "lastName": "Kubrick"
}

pk

Type data: number

firstName

Type data: string

lastName

Type data: string

Event system

LSF has a built-in event system that allows you to listen to events and trigger custom actions. You can subscribe to or unsubscribe from event at any time after the Label Studio instance is initialized.

Using events

Subscribe to an event

const callback = () => {
  console.log("Event triggered");
};
labelStudio.on("event", callback);

Unsubscribe from an event

const callback = () => {
  console.log("Event triggered");
};
labelStudio.off("event", callback);

Available events

Top-level events

This events group contains top-level events. Those events are not related to any internal entities of the LSF.

labelStudioLoad

Label Studio instance is loaded.

Event handler arguments

storageInitialized

The internal storage is initialized.

Event handler arguments

Task events

This events group contains events related to the task.

skipTask

User clicked the “Skip” button.

Event handler arguments

unskipTask

User clicked the “Cancel Skip” button.

nextTask

User clicked the “Next” (chevron right) button.

prevTask

User clicked the “Previous” (chevron left) button.

submitDraft

Draft is sent to the server.

Annotation events

This events group contains events related to the annotation.

beforeSaveAnnotation

Annotation is going to be saved as the result of the submit or update action. Returning false from this event will prevent saving the annotation.

submitAnnotation

Annotation is submitted.

updateAnnotation

Annotation is updated.

selectAnnotation

Annotation is selected.

deleteAnnotation

Annotation is deleted.

groundTruth

Annotation is set as Ground Truth (the star button clicked).

selectHistory

Step in the annotation history is selected.

Region events

This events group contains events related to the regions. Regions are the special entities used in segmentation tasks like image segmentation, audio segmentation, etc.

entityCreate

Region is created.

entityDelete

Region is deleted.

onSubmitAnnotation: function(ls, annotation) {
  console.log(annotation)
}

onUpdateAnnotation: function(ls, annotation) {
  console.log(result)
}

onDeleteAnnotation: function(ls, annotation) {
  console.log(result)
}

onEntityCreate: function(region) {
  console.log(region)
}

onEntityDelete: function(region) {
  console.log(region)
}

onSkipTask: function(ls) {
  console.log(result)
}

onLabelStudioLoad: function(ls) {
  console.log(result)
}