Library for manipulating text ranges and selections, and assorted other programs that use that

View the Project on GitHub dwachss/bililiteRange

Cross-Browser Text Ranges and Selections

bililiteRange(element) returns an abstraction of a range of characters within element, initially all of the element. The range never extends outside the element. element is a DOM element. It’s not a constructor; you don’t have to use new bililiteRange() (though that does work).

It works for <input>, <textarea> and any other HTMLELement (though they should have contenteditable set to be useful).

It treats the elements as a series of characters, which means that elements should use white-space: pre because it will not collapse white space and counts newlines as characters. It also doesn’t count display: block as ending in a newline (unless it actually does). The major use case is a pretty-printing editor (I use Prism).


Any method that does not have an explicit return value returns the range itself, so methods can be chained: range.all('foo bar').bounds('start').text('baz ').sendkeys('{ArrowLeft}').select() sets the text of the element to "baz foo bar", with the selection point right after baz.


Returns or sets the beginning of the range, so you can use it like an array: range[0] = 2. Set returns the new value.


Returns or sets the end of the range, so you can use it like an array: range[1] = 6. Set returns the new value. The two together are equivalent to range.bounds[2,6]).


Returns the entire text of the element without changing the bounds of the range.

all(text: string)

Sets the entire text of the element to text and sets the bounds to cover the entire range.


Returns an array, [start, end] of the bounds of the current range. start is always >= 0 and end is always <= length of the text of the entire element.

bounds(b: array)

Sets the bounds of the current range to the b. Does not throw an error for limits out of bounds, just silently limits them.

bounds(n: number)

Shortcut for bounds([n,n]).

bounds(r: bililiteRange)

Sets the bounds of the current range to those of r.

bounds(s: string)

Looks for a function bililiteRange[s] that is called with this set to the current bililiteRange, and sets the bounds. Predefined functions include:

This only uses the actual selection if the element is the same as document.activeElement; if the element is not active, then bililiteRange sets up event listeners to remember the selection from when the element was the active element, and uses that.

Several other bounds functions are defined, and it is possible to create new bounds functions. See the documentation.


Return a new bililiteRange with the same bounds as this one.


Returns an object tied to the underlying element, useful for storing element (rather than per range). Similar to jQuery’s data. See the documentation for bililiteRange data.


Returns element.ownerDocument.


Returns the DOM element that the range was defined on.


Returns range.text().length.

live(on = true)

If the on argument is true (or undefined, since true is the default), makes this range “live”: sets up an input listener that will adjust the bounds to track changes in the text of the element. Changes after the bounds do nothing; changes before the bounds move the bounds, and changes within the bounds change the bounds so the range still refers to the replacement text. Similar to bookmarks in Microsoft Word, except that deleting the entire text of the range does not remove or move the range; it just becomes a zero-length range.

live(false) removes the input listener, so the range is no longer adjusted.

Under the hood, there is a single input listener that goes through a Set of ranges that are adjusted. That means there is a potential memory leak: any live range will not be garbage collected. Do to remove the reference.

scrollIntoView([fn: function])

Does its best to scroll the beginning of the range into the visible part of the element, by analogy to Element.scrollIntoView(). Note that it does not move the element itself, just sets element.scrollTop so that the start of the range is within the visible part of the element. If it already visible, does nothing. This only scrolls vertically, not horizontally.

The function passed in used to do the scrolling, with one parameter that is the target scrollTop, and this set to the element itself. So, to animate the scrolling, use range.scrollIntoView( top => { $(this).animate({scrollTop: top}) }). The default function is top => { this.scrollTop = top }.


If the element is the same as document.activeElement, then set the window selection to the current range. if the element is not active, change the saved selection to the current range, and use that for bounds('selection'). Sets up event listeners so that when the element is activated, the saved selection is restored (except if the element is activated by a mouse click, where the click location determines the selection). This means that tabbing into an element restores the previous selection.

Note that this does not set the focus on the element; use range.element.focus() to do that. Note also that elements that are not editable and do not have a tabindex cannot be focussed.


Short for range.bounds('selection').text(), to get the text currently selected.

selection(s: string)

Short for range.bounds('selection').text(s, 'end').select(); useful for inserting text at the insertion point. This just inserts the string argument straight in the text; for a more sophisticated function, see sendkeys below.

sendkeys(s: string)

Basically does text(s, ‘end’) but interprets brace-surrounded words (like '{Backspace}' as special commands that execute the corresponding functions in bililiteRange.sendkeys, in this case bililiteRange.sendkeys['{Backspace}']. See the full documentation.


Returns the text of the current range.

text(s: string, [opts])

Sets the text of the current range to s. The bounds are adjusted to cover the new text.

For consistency with Input Events, also triggers beforeinput and input events on the element. The inputType is determined by opts.inputType, with a default value of 'insertText'. The data field is set to s (potentially an empty string, unlike Chrome, which sets the data field to undefined if no text is being inserted). Since this is not enough to fully determine the change made, another field is set on the Event object:

let e = new Event('input');
e.inputType = opts.inputType || 'insertText';
e.bililiteRange = {
	oldText, // the content of the range before it was changed
	newText, // s, the text inserted
	start,  // bounds[0], where the text was inserted
	unchanged // boolean, true if oldText == newText

bililiteRange also sets up event listeners on InputEvents to add this field to browser-generated event objects.


Returns the offsetTop for the range–the pixels from the top of the padding box of the element to the beginning of the range. Will be negative if the element is scrolled so that the range is above the visible part of the element. To scroll the element so that the range is at the top of the element, set range.element.scrollTop = See range.scrollIntoView() above.


Returns element.document.defaultView.


Wraps the range with the DOM Node passed in (generally will be an HTML element). Only works with ranges defined on the DOM itself; throws an error for ranges in <input> or <textarea> elements. Depending on the browser, will throw an error for invalid HTML (like wrapping a <p> with a <span>). For example, to highlight the range, use range.wrap ( document.createElement('strong') );



Even though bililiteRange is a function, not a class (use r = bililiteRange(el), not r = new bililiteRange(el)), it is based on internal classes, and adding a method to bililiteRange.prototype makes it available to all ranges. So

bililiteRange.prototype.log = () => {
	console.log(this.bounds(), ': ', this.text());
	return this; // always good to return this to allow for chaining

allows for

let r = bililiteRange(el);
r.all('hello, world').bounds([0,5]).log(); // on the console: [0,5]: "hello"

As a shorthand (based on jQuery extend) there is


Adds all the enumerable members of obj to bililiteRange.prototype, with Object.assign (bililiteRange.prototype, obj).

bililiteRange.override (name, fn)

Allows monkey patching methods. Replaces bililiteRange.prototype[name] with a function that creates this.super with the old value of bililiteRange.prototype[name] and calls the fn. So, for example, to censor forbidden words:

bililiteRange.override ('text', function (text, opts) { // need to use "function", not arrow notation, to use "this"
	text = censor(text); // left as an exercise for the reader
	return this.super(text, opts);



Creates an event of type opts.type, then extends it with the rest of opts, and dispatches it on range.element. Basically does:

let event =  new Event(opts.type);
for (let key in opts) event[key] = opts[key];

Note that dispatchEvent is synchronous, meaning that the event handlers will all be run before returning from range.dispatch().

listen(s, fn)

Shorthand for this.element.addEventListener(s, fn).

dontlisten(s, fn)

Shorthand for this.element.removeEventListener(s, fn).


There are a few methods and fields defined on the bililiteRange namespace, that act as “global” variables, applicable to all bililiteRanges


bililiteRange.addStartupHook ( fn ) adds fn to a Set of functions that are run when a bililiteRange is defined on an element for the first time. The function is called with fn (element, range, data), the HTMLELement, the range that is being created, and This is how to add listeners for monitored data:

bililiteRange.createOption ('size', {value: 100, monitored: true});
bililiteRange.addStartupHook( (element, range, data) => {
	console.log (`starting an element with size = ${data.size}`); // the listener below will only be called on changes to the data
	element.addEventListener ( 'data-size', evt => console.log (`changing size to ${evt.detail}`);


See the bounds documentation.


See the data documentation.


bililiteRange.diff (oldText, newText) is a convenience function that compares two texts and returns an object:

	unchanged, // true if oldText == newText, false otherwise
	start, // character position where the two texts start to differ
	oldText, // part of oldText that has been removed
	newText // part of newText that has been added


See above.


See the sendkeys documentation.


Returns the version number.

Other files


Implements searching with ranges. See the documentation.


Adds useful functions for searching and keeping the ranges up-to-date with changes in the underlying text. Depends on bililiteRange.js. See the documentation.


Adds an undo/redo stack to editable elements. Depends on bililiteRange.js and my historystack. See the documentation.


Implements the ex line-editor. Depends on bililiteRange.js, bililiteRange.util.js and bililiteRange.undo.js. See the documentation.


Implements all the pieces to use bililite.ex.js, with keystroke mapping, toolbar buttons, and jQuery integration. Works with my toolbar and status. See the documentation.


jQuery wrapper for bililiteRange.prototype.sendkeys, with a keydown handler that allows for synthetic (untrusted) keydown events to insert text. See the documentation.