Package {webformscore}

WebForms Core for R

Description

An R implementation of the server-side part of WebForms Core, a stateless server-driven user interface technology for building web interfaces through server-side UI manipulation. The server-side class acts as a Commander that generates commands, while WebFormsJS serves as the client-side Executor that applies them. Commands range from atomic operations, such as adding elements and modifying text and attributes, to higher-level operations such as iterative processing and render.

Usage

GS
US
RS
NUL

InputPlace
OutputPlace
Fetch
HtmlEvent
HtmlEventListener
WasmLanguage

ext_child(text, value)
ext_parent(text)
ext_criteria(text, value)
ext_append_fetch_replace(text, searchValue, value)
ext_line_break(text, encodeLine = FALSE)
ext_to_js_string(text)
ext_to_js_object(text)
ext_to_js_return_object(text)

Arguments

Details

Commander and Executor

The package implements the server side of WebForms Core. A WebForms object accumulates commands. The result is sent to the browser using response(), export_to_html_comment(), or export_to_line_break(), where WebFormsJS applies the commands to the DOM.

The WebForms class

Create an instance with WebForms$new() and call its public methods to append commands. The main families of methods are:

• Buffer: add(), add_to_up(), get_web_forms_data(), append_form(), clean(), get_line_by_index(), update_line_by_index().

• Add helpers (append to existing value): add_id(), add_name(), add_value(), add_class(), add_style(), add_attribute(), add_text(), add_tag(), add_option_tag(), add_check_box_tag(), and others.

• Set helpers (replace existing value): set_id(), set_name(), set_value(), set_class(), set_style(), set_text(), set_attribute(), set_background_color(), set_text_color(), set_font_size(), set_visible(), set_disabled(), and others.

• Insert helpers (create only, never replace): insert_id(), insert_name(), insert_value(), insert_class(), insert_style(), insert_text(), insert_attribute(), and others.

• Delete: delete(), delete_parent(), delete_id(), delete_name(), delete_value(), delete_class(), delete_style(), delete_attribute(), and others.

• Events: set_post_event(), set_post_event_listener(), set_get_event(), set_put_event(), set_patch_event(), set_delete_event(), set_send_event(), set_comment_event(), set_sse_event(), set_web_socket_event(), set_wasm_event(), set_front_event(), set_method_event(), assign_confirm_event(), trigger_event(), and matching remove_*_event() methods.

• Flow control: start_index(), start_state(), go_to(), is_equal_to(), is_not_equal_to(), is_greater_than(), is_less_than(), exist(), not_exist(), is_true(), is_false(), include(), not_include(), element_exists(), for_each(), then(), else_(), start_bracket(), end_bracket(), break_(), repeat_(), isole(), render(), async(), delay().

• Save and cache: save_id(), save_value(), save_text(), cache_id(), cache_value(), cache_text(), and the set_*_save_value() / set_*_cache_value() family.

• Pre-runner modifiers: assign_delay(), assign_interval(), assign_repeat(), delete_interval().

• Browser: change_url(), set_head_title(), clipboard_write_text(), scroll_to(), history_go(), reload_page(), redirect().

• Call and message: load_url(), call_script(), call_method(), call_post_back(), call_get_back(), call_sse_back(), alert(), message(), console_message(), create_debugger(), comment().

• Output: response(), get_forms_action_data(), get_forms_action_data_line_break(), export_to_html_comment(), export_to_line_break().

The Security class

Security$new() creates an object with a single public method safe_value(value) that prepares a string for embedding in a command: it escapes a leading "@" to prevent command forgery, replaces newlines with "$[ln];", replaces ",@" with "$[co];@", and strips ASCII control characters 28–31.

Separator constants

GS separates fields inside one command. US joins list items inside one field. RS is used by Fetch helpers. NUL is the default splitter argument of add_attribute() and insert_attribute().

Place criteria

InputPlace contains both constants (such as document, window, html, head, parent, current, target) and helper functions (such as id(), name(), tag(), class(), attribute(), query()). OutputPlace is a direct alias.

Fetch helpers

Fetch provides access to client-side values (for example get_value(), get_text(), get_attribute()), to the browser environment (such as href, scroll_x, user_agent, screen_width), to the current event (such as event, event_key, event_client_x), and to the save and cache storage (save(), cache()).

Extension helpers

ext_child(), ext_parent(), ext_criteria(), ext_append_fetch_replace(), ext_line_break(), ext_to_js_string(), ext_to_js_object(), and ext_to_js_return_object() mirror the extension methods used by the Commander API in other languages.

Value

WebForms

An R6 class generator. Calling WebForms$new() returns a new WebForms object, the main Command builder.

Security

An R6 class generator. Calling Security$new() returns a new Security object with the method safe_value().

GS, US, RS, NUL

Single-character strings. GS is ASCII 29 (group separator), RS is ASCII 30 (record separator), US is ASCII 31 (unit separator), and NUL is ASCII 0 (null character).

InputPlace, OutputPlace

A named list of constants and helper functions for building WebForms Place Criteria (WPC) strings. OutputPlace is an alias of InputPlace.

Fetch

A named list of helpers for reading client-side values or embedding dynamic values in commands.

HtmlEvent, HtmlEventListener

Named lists of HTML event attribute names (with the on prefix) and event listener names (without the on prefix).

WasmLanguage

A named list of WebAssembly language identifiers.

ext_*

Each returns a character string.

See Also

Useful links:

• https://github.com/webforms-core

Examples

# Build a simple command payload without starting an HTTP server.
form <- WebForms$new()

form$set_font_size("<form>", 16)
form$set_background_color("<form>", "lightblue")
form$add_tag("<form>", "h3")
form$set_text("<h3>", "Welcome!")

cat(form$response())

# Separator constants.
GS
US
RS
nchar(NUL)

# Place criteria helpers.
InputPlace$id("my-id")
InputPlace$tag("div")
OutputPlace$class("active")

# Fetch helpers.
Fetch$get_value("<select>")
Fetch$date_hours

# Security helper.
sec <- Security$new()
sec$safe_value("line1")
sec$safe_value("@not-a-fetch-command")

# Extension helpers.
ext_child("a", "b")
ext_parent("a|b")
ext_line_break("a\r\nb", TRUE)
ext_to_js_string("value")