gramlot.

Course · Lesson 12 of 20

Format values without changing Data

Separate raw values, formatted text, pointer expressions and date interpretation.

Reading · Practice2 sectionsPrerequisites: Publish messages and ask before acting
Course contents
Orientation
  1. 01 Install Gramlot and create Hello world
  2. 02 Connect text and colour to Data
  3. 03 Explore Data and Source with the inspector
  4. 04 Use relative and symbolic paths, then dataFormula
  5. 05 Call the server with dataRpc and .remote
Start a project
  1. 01 Create your first project
  2. 02 Read and compose Source
  3. 03 Initialize structured Data
  4. 04 Connect fields and values
Build a form
  1. 05 Accept values, preserve drafts
  2. 06 Declare a calculation
  3. 07 Run an action at the right time
  4. 08 Name behavior and understand lifecycle
Compose an interface
  1. 09 Arrange an application with containers
  2. 10 Style the page you own
  3. 11 Publish messages and ask before acting
  4. 12 Format values without changing Data
Connect services
  1. 13 Call an endpoint
  2. 14 Load a Source fragment
  3. 15 Load Data when it is read
  4. 16 Save, restore and send Data deliberately
Deliver your work
  1. 17 Organize pages and choose a host
  2. 18 Read the JavaScript edition
  3. 19 Deliver the JavaScript edition offline
  4. 20 Explain and change a complete form

Presentation is a projection

gramlot.format turns supported values into text using a numeric pattern or temporal options. Locale and instant timezone come from the page context unless deliberately overridden. Formatting a value does not replace the original value in Data.

Pointer templates and expressions let attributes project Data into text or another attribute value. In the gallery, read the literal expression and identify its inputs before changing a control. A displayed unit such as px is not part of the stored number.

Date parsing has a different job

parseDateExpression interprets supported English and Italian date expressions. The caller supplies a working date, examines ok and distinguishes a date from a period. It does not automatically edit a field or write Data.

For example, tomorrow requires a reference day. Invalid dates return an error result. Keep parsing, typed storage and display formatting separate so changing the locale cannot silently become a change to the application’s underlying value.

Your turn

Try it yourself

  1. Open Pointer templates and expressions and follow a numeric Data value into its displayed attribute.
  2. Change that value and compare the raw inspector value with the rendered text.
  3. In the date-expression reference, compare a single date, a period and an invalid date; identify the result kind for each.

Check your understanding

Does displaying a number with two decimal places make all later arithmetic exact to two places?

Show the answer and expected result

No. Formatting produces text; it does not change the stored numeric value or establish a rounding policy for subsequent arithmetic. Financial rules require explicit types and rounding. Likewise, parsing a period does not make it a single date.

Working examples and reference