Text input fields

A text input field stores a string as its value and a string as its text. Its value is always a valid string, while its text could be any string entered into its editor.

Text input field

Text input field with editor open

Text input field on collapsed block



  "type": "example_textinput",
  "message0": "text input: %1",
  "args0": [
      "type": "field_input",
      "name": "FIELDNAME",
      "text": "default text",
      "spellcheck": false


Blockly.Blocks['example_textinput'] = {
  init: function() {
        .appendField("text input:")
        .appendField(new Blockly.FieldTextInput('default text'),

The text input constructor takes in an optional value and an optional validator. The value should cast to a string. If it is null or undefined, an empty string will be used.

The JSON definition also allows you to set the spellcheck option.

Serialization and XML

The XML for a text input field looks like so:

<field name="FIELDNAME">text</field>

Where the field's name attribute contains a string referencing a text input field, and the inner text is the value to apply to the field. The inner text value follows the same rules as the constructor value.



The setSpellcheck function can be used to set whether the field spellchecks its input text or not.

Text input fields with and without spellcheck

Spellchecking is on by default.

This applies to individual fields. If you want to modify all fields change the Blockly.FieldTextInput.prototype.spellcheck_ property.

Creating a text input validator

A text input field's value is a string, so any validators must accept a string and return a string, null, or undefined.

Here is an example of a validator that removes all 'a' characters from the string:

function(newValue) {
  return newValue.replace(/a/g, '');