Tutorial: setFieldValue

To set the value of a field use setFieldValue.

formsApi.setFieldValue('fieldName', 'value')

In the case of multiple steps where field names occour twice or more, the input parameter can be extended with @{stepindex} to target the field on a specific step.

formsApi.setFieldValue('fieldName@1', 'value')

To set the values of multiple fields at once use setFieldValues.

formsApi.setFieldValues({
            "field1": "value1",
            "field2": "value2",
            "field3": "value3"
        })