# Chawan's command API As described in the [config](config.md) documentation, keypress combinations can be bound to actions. An action can be either a JavaScript expression, or a command defined in the `[cmd]` section of config.toml. For example, the following works: ``` gpn = 'n => pager.alert(n)' # e.g. 2gpn prints `2' to the status line ``` Note however, that JavaScript functions must be called with an appropriate `this` value. Unfortunately, this also means that the following does not work: ``` gpn = 'pager.alert' # broken!!! ``` To work around this limitation, actions have to wrap the target function in a closure, as above. However, this has very poor reusability; for more complex actions, you would have to copy and paste the entire function every time you re-bind it or call it from a different function. To fix this, it is possible to define a command in the `[cmd]` section: ```toml [cmd.my.namespace] showNumber = 'n => pager.alert(n)' ``` `my.namespace` can be anything you want; it is to avoid collisions when including multiple configs. Avoid setting it to `pager` or `line`, because these are used by the default config. Now you can call `cmd.my.namespace.showNumber()` from any other function, or just include it in an action: ```toml 'gpn' = 'cmd.my.namespace.showNumber' ``` ## Interfaces ### Client The global object (`globalThis`) implements the `Client` interface. Documented functions of this are:

Property	Description
`quit()`	Exit the browser.
`suspend()`	Temporarily suspend the browser, by delivering the client process a SIGTSTP signal. Note: this suspends the entire process group.
`readFile(path)`	Read a file at `path`. Returns the file's content as a string, or null if the file does not exist.
`writeFile(path, content)`	Write `content` to the file at `path`. Throws a TypeError if this failed for whatever reason.
`getenv(name, fallback = null)`	Get an environment variable by `name`. Returns `fallback` if the variable does not exist.
`setenv(name, value)`	Set an environment variable by `name`. Throws a type error if the operation failed (e.g. because the variable's size exceeded an OS-specified limit.)
`pager`	The pager object. Implements `Pager`, as described below.
`line`	The line editor. Implements `LineEdit`, as described below.
`config`	The config object. A currently incomplete interface for retrieving and setting configuration options. In general, names are the same as in config.toml, except all `-` (ASCII hyphen) characters are stripped and the next character is upper-cased (underscore). e.g. `external.cgi-dir` can be queried as `config.external.cgiDir`, etc. Setting individual options sometimes works, but sometimes they do not get propagated as expected. Consider this an experimental API. Currently, `siteconf`, `protocol` and `omnirule` values are not exposed to JS. The configuration directory itself can be queried as `config.dir`.

`Client` also implements various web standards normally available on the `Window` object on websites, e.g. fetch(). Note however that it does *not* give access to JS objects in buffers, so e.g. `globalThis.document` is not available. ### Pager `Pager` is a separate interface from `Client` that gives access to the pager (i.e. browser chrome). It is accessible as `globalThis.pager`, or simply `pager`. Following properties (functions/getters) are defined by `Pager`:

Property	Description
`load(url)`	Put the specified address into the URL bar, and optionally load it. Note that this performs auto-expansion of URLs, so Chawan will expand any matching omni-rules (e.g. search), try to open schemeless URLs with the default scheme/local files, etc. Opens a prompt with the current URL when no parameters are specified; otherwise, the string passed is displayed in the prompt. If this string ends with a newline (e.g. `pager.load("about:chawan\n")`), the URL is loaded directly.
`loadSubmit(url)`	Act as if `url` had been input into the address bar. Same as `pager.load(url + "\n")`.
`gotoURL(url, options = {replace: null, contentType: null, save: false})`	Go to the specified URL immediately (without a prompt). This differs from `loadSubmit` in that it loads the exact URL as passed (no prepending https, etc.) When `replace` is set, the new buffer may replace the old one if it loads successfully. When `contentType` is set, the new buffer's content type is forcefully set to that string. When `save` is true, the user is prompted to save the resource instead of displaying it in a buffer.
`nextBuffer()`, `prevBuffer()`, `nextSiblingBufer()`, `prevSiblingBuffer()`, `parentBuffer()`	Traverse the buffer tree. `nextBuffer()`, `prevBuffer()` do a depth-first traversal; ``nextSiblingBufer()`, `prevSiblingBuffer()` cycle through siblings, and `parentBuffer()` returns to the parent.
`dupeBuffer()`	Duplicate the current buffer by loading its source to a new buffer.
`discardBuffer(buffer = pager.buffer, dir = pager.navDirection)`	Discard `buffer`, then move back to the buffer opposite to `dir`. Possible values of `dir` are: "prev", "next", "prev-sibling", "next-sibling", "parent", "first-child", "any".
`discardTree()`	Discard all child buffers of the current buffer.
`reload()`	Open a new buffer with the current buffer's URL, replacing the current buffer.
`reshape()`	Reshape the current buffer (=render the current page anew.)
`redraw()`	Redraw screen contents. Useful if something messed up the display.
`toggleSource()`	If viewing an HTML buffer, open a new buffer with its source. Otherwise, open the current buffer's contents as HTML.
`lineInfo()`	Display information about the current line.
`searchForward()`, `searchBackward()`	Search forward/backward for a string in the current buffer.
`isearchForward()`, `isearchBackward()`	Incremental-search forward/backward for a string, highlighting the first result.
`gotoLine(n?)`	Go to the line passed as the first argument. If no arguments were specified, an input window for entering a line is shown.
`searchNext(n = 1)`, `searchPrev(n = 1)`	Jump to the nth next/previous search result.
`peek()`	Display an alert message of the current URL.
`peekCursor()`	Display an alert message of the URL or title under the cursor. Multiple calls allow cycling through the two. (i.e. by default, press u once -> title, press again -> URL)
`showFullAlert()`	Show the last alert inside the line editor.
`ask(prompt)`	Ask the user for confirmation. Returns a promise which resolves to a boolean value indicating whether the user responded with yes. Can be used to implement an exit prompt like this: ``` q = 'pager.ask("Do you want to exit Chawan?").then(x => x ? pager.quit() : void(0))' ```
`askChar(prompt)`	Ask the user for any character. Like `pager.ask`, but the return value is a character.
`extern(cmd, options = {env: { ... }, suspend: true, wait: false})`	Run an external command `cmd`. By default, the `$CHA_URL` and `$CHA_CHARSET` variables are set; change this using the `env` option. `options.suspend` suspends the pager while the command is being executed, and `options.wait` makes it so the user must press a key before the pager is resumed. Returns true if the command exit successfully, false otherwise. Warning: this has a bug where the output is written to stdout even if suspend is true. Redirect to /dev/null in the command if this is not desired. (This will be fixed in the future.)
`externCapture(cmd)`	Like extern(), but redirect the command's stdout string into the result. null is returned if the command wasn't executed successfully, or if the command returned a non-zero exit value.
`externInto(cmd, ins)`	Like extern(), but redirect `ins` into the command's standard input stream. `true` is returned if the command exits successfully, otherwise the return value is `false`.
`externFilterSource(cmd, buffer = null, contentType = null)`	Redirects the specified (or if `buffer` is null, the current) buffer's source into `cmd`. Then, it pipes the output into a new buffer, with the content type `contentType` (or, if `contentType` is null, the original buffer's content type). Returns `undefined`. (It should return a promise; TODO.)
`buffer`	Getter for the currently displayed buffer. Returns a `Buffer` object; see below.

### Buffer Each buffer is exposed as an object that implements the `Buffer` interface. To get a reference to the currently displayed buffer, use `pager.buffer`. Important: there exists a quirk of questionable value on pager, where accessing properties that do not exist on the pager will dispatch those to the current buffer (`pager.buffer`). So if you see e.g. `pager.url`, that is actually equivalent to `pager.buffer.url`, because `Pager` has no `url` getter. Following properties (functions/getters) are defined by `Buffer`:

Property	Description
`cursorUp(n = 1)`, `cursorDown(n = 1)`	Move the cursor upwards/downwards by n lines, or if n is unspecified, by 1.
`cursorLeft(n = 1)`, `cursorRight(n = 1)`	Move the cursor to the left/right by n cells, or if n is unspecified, by 1. Note: `n` right now represents cells, but really it should represent characters. (The difference is that right now numbered cursorLeft/cursorRight is broken for double-width chars.)
`cursorLineBegin()`, `cursorLineEnd()`	Move the cursor to the first/last cell of the line.
`cursorLineTextStart()`	Move the cursor to the first non-blank character of the line.
`cursorNextWord()`, `cursorNextViWord()`, `cursorNextBigWord()`	Move the cursor to the beginning of the next [word](#word-types).
`cursorPrevWord()`, `cursorPrevViWord()`, `cursorPrevBigWord()`	Move the cursor to the end of the previous [word](#word-types).
`cursorWordEnd()`, `cursorViWordEnd()`, `cursorBigWordEnd()`	Move the cursor to the end of the current [word](#word-types), or if already there, to the end of the next word.
`cursorWordBegin()`, `cursorViWordBegin()`, `cursorBigWordBegin()`	Move the cursor to the beginning of the current [word](#word-types), or if already there, to the end of the previous word.
`cursorNextLink()`, `cursorPrevLink()`	Move the cursor to the beginning of the next/previous clickable element.
`cursorLinkNavDown(n = 1)`, `cursorLinkNavUp(n = 1)`	Move the cursor to the beginning of the next/previous clickable element. Buffer scrolls pagewise, wrap to beginning/end if content is less than one page length.
`cursorNextParagraph(n = 1)`, `cursorPrevParagraph(n = 1)`	Move the cursor to the beginning/end of the nth next/previous paragraph.
`cursorNthLink(n = 1)`	Move the cursor to the nth link of the document.
`cursorRevNthLink(n = 1)`	Move the cursor to the nth link of the document, counting backwards from the document's last line.
`pageUp(n = 1)`, `pageDown(n = 1)`, `pageLeft(n = 1)`, `pageRight(n = 1)`	Scroll up/down/left/right by n pages.
`halfPageUp(n = 1)`, `halfPageDown(n = 1)`, `halfPageLeft(n = 1)`, `halfPageRight(n = 1)`	Scroll up/down/left/right by n half pages.
`scrollUp(n = 1)`, `scrollDown(n = 1)`, `scrollLeft(n = 1)`, `scrollRight(n = 1)`	Scroll up/down/left/right by n lines.
`click()`	Click the HTML element currently under the cursor.
`cursorFirstLine()`, `cursorLastLine()`	Move to the first/last line in the buffer.
`cursorTop()`, `cursorMiddle()`, `cursorBottom()`	Move to the first/middle/bottom line on the screen. (Equivalent to H/M/L in vi.)
`lowerPage(n = this.cursory)`	Move cursor to line n, then scroll up so that the cursor is on the top line on the screen. (`zt` in vim.)
`lowerPageBegin(n = this.cursory)`	Move cursor to the first non-blank character of line n, then scroll up so that the cursor is on the top line on the screen. (`z` in vi.)
`centerLine(n = this.cursory)`	Center screen around line n. (`zz` in vim.)
`centerLineBegin(n = this.cursory)`	Center screen around line n, and move the cursor to the line's first non-blank character. (`z.` in vi.)
`raisePage(n = this.cursory)`	Move cursor to line n, then scroll down so that the cursor is on the top line on the screen. (zb in vim.)
`lowerPageBegin(n = this.cursory)`	Move cursor to the first non-blank character of line n, then scroll up so that the cursor is on the last line on the screen. (`z^` in vi.)
`nextPageBegin(n = this.cursory)`	If n was given, move to the screen before the nth line and raise the page. Otherwise, go to the previous screen's last line and raise the page. (`z+` in vi.)
`cursorLeftEdge()`, `cursorMiddleColumn()`, `cursorRightEdge()`	Move to the first/middle/last column on the screen.
`centerColumn()`	Center screen around the current column.
`findNextMark(x = this.cursorx, y = this.cursory)`, `findPrevMark(x = this.cursorx, y = this.cursory)`	Find the next/previous mark after/before `x`, `y`, if any; and return its id (or null if none were found.)
`setMark(id, x = this.cursorx, y = this.cursory)`	Set a mark at (x, y) using the name `id`. Returns true if no other mark exists with `id`. If one already exists, it will be overridden and the function returns false.
`clearMark(id)`	Clear the mark with the name `id`. Returns true if the mark existed, false otherwise.
`gotoMark(id)`	If the mark `id` exists, jump to its position and return true. Otherwise, do nothing and return false.
`gotoMarkY(id)`	If the mark `id` exists, jump to the beginning of the line at its Y position and return true. Otherwise, do nothing and return false.
`getMarkPos(id)`	If the mark `id` exists, return its position as an array where the first element is the X position and the second element is the Y position. If the mark does not exist, return null.
`cursorToggleSelection(n = 1, opts = {selectionType: "normal"})`	Start a vim-style visual selection. The cursor is moved to the right by `n` cells. selectionType may be "normal" (regular selection), "line" (line-based selection) and "column" (column-based selection).
`getSelectionText()`	Get the currently selected text. Returns a promise, so consumers must `await` it to get the text.
`markURL()`	Convert URL-like strings to anchors on the current page.
`toggleImages()`	Toggle display of images in this buffer.
`saveLink()`	Save URL pointed to by the cursor.
`saveSource()`	Save the source of this buffer.
`setCursorX(x)`, `setCursorY(y)`, `setCursorXY(x, y)`, `setCursorXCenter(x)`, `setCursorYCenter(y)`, `setCursorXYCenter(x, y)`	Set the cursor position to `x` and `y` respectively, scrolling the view if necessary. Variants that end with "Center" will also center the screen around the position if it is outside the screen.
`url`	Getter for the buffer's URL. Note: this returns a `URL` object, not a string.
`hoverTitle`, `hoverLink`, `hoverImage`	Getter for the string representation of the element title/link/image currently under the cursor. Returns the empty string if no title is found.
`cursorx`, `cursory`	The x/y position of the cursor inside the buffer. Note that although the status line is 1-based, these values are 0-based.
`fromx`, `fromy`	The x/y position of the first line displayed on the screen.
`numLines`	The number of lines currently loaded in the buffer.
`width`, `height`	The width and height of the buffer's window (i.e. the visible part of the canvas).
`process`	The process ID of the buffer.
`title`	Text from the `title` element, or the buffer's URL if there is no title.
`parent`	Parent buffer in the buffer tree. May be null.
`children`	Array of child buffers in the buffer tree.
`select`	Reference to the current `select` element's widget, or null if no `select` element is open. This object implements the `Select` interface, which is somewhat compatible with the `Buffer` interface with some exceptions. (TODO: elaborate)

### LineEdit The line editor at the bottom of the screen is exposed to the JavaScript context as `globalThis.line`, or simply `line`, and implements the `LineEdit` interface. Note that there is no single `LineEdit` object; a new one is created every time the line editor is opened, and when the line editor is closed, `globalThis.line` simply returns `null`. Following properties (functions/getters) are defined by `LineEdit`:

Property	Description
`submit()`	Submit line.
`cancel()`	Cancel operation.
`backspace()`	Delete character before cursor.
`delete()`	Delete character after cursor.
`clear()`	Clear text before cursor.
`kill()`	Clear text after cursor.
`clearWord()`	Delete word before cursor.
`killWord()`	Delete word after cursor.
`backward()`, `forward()`	Move cursor backward/forward by one character.
`nextWord()`, `prevWord()`	Move cursor to the next/previous word by one character.
`begin()`, `end()`	Move cursor to the beginning/end of the line.
`escape()`	Ignore keybindings for next character.
`nextHist()`, `prevHist()`	Jump to the previous/next history entry.