getSelection() does not return a single character selection

[theflyingape]

Relates to: #2244
This works fine when a double-click highlights a word selection > 1 character. But if the selection only highlights a single character, getSelection() returns an empty string. Is this by design?

Details

• Browser and browser version: Chrome 78
• OS version: Linux
• xterm.js version: 4.3.0

Steps to reproduce

1. ITerminalOptions.wordSeparator = ` .:;?!"'<>(/)[=]`
2. term.write('Sex (M/F)? ')
3. double-click the 'M'
4. getSelection() returns ''

Online example: https://play.ddgame.us

[Tyriar]

I can't repro?

[theflyingape]

Did you double-click the M? It works if you click&hold and select a single character.
Perhaps this missing info is crucial here... my getSelection() occurs within the onSelectionChange() event, i.e.,

	term.onSelectionChange(() => {
		if (carrier) {
			let word = term.getSelection()
			if (word.length > 0 && word.length < 64) {
				socket.send(word + '\x0D')
				term.clearSelection()
			}
		}
	})

• https://play.ddgame.us press RETURN to connect and double-click NEW -- works.
• double-click Handle -- works.
• click&hold to select REAL name -- works.
• type 121212 for a fake date
• now double-click M -- nothing. click&hold to select F -- works.
  

[Tyriar]

@theflyingape I do see double clicking not sending sometimes, maybe the event isn't firing or something?

[daniel-j-davis]

I took a shot at looking into this and seems like it's related to onMouseUp in the SelectionService...

xterm.js/src/browser/services/SelectionService.ts

Line 665 in afc3910

private _onMouseUp(event: MouseEvent): void {

xterm.js/src/browser/services/SelectionService.ts

Line 670 in afc3910

if (this.selectionText.length <= 1 && timeElapsed < ALT_CLICK_MOVE_CURSOR_TIME) {

xterm.js/src/browser/services/SelectionService.ts

Line 671 in afc3910

if (event.altKey && this._bufferService.buffer.ybase === this._bufferService.buffer.ydisp) {

The problem is that if the length of selectionText is <= 1, but event.altKey doesn't return true, the selection gets thrown away and this._onSelectionChange.fire() doesn't get called. Is there a reason that we can't just always call this._onSelectionChange.fire(), even if event.altKey is true?

Thoughts? @Tyriar @theflyingape

[Tyriar]

@daniel-j-davis good find! Moving this event.altKey up one line would probably fix it, do you want to do a PR?

xterm.js/src/browser/services/SelectionService.ts

Lines 670 to 671 in afc3910

	if (this.selectionText.length <= 1 && timeElapsed < ALT_CLICK_MOVE_CURSOR_TIME) {
	if (event.altKey && this._bufferService.buffer.ybase === this._bufferService.buffer.ydisp) {

To verify, make sure alt+click still works by moving the cursor horizontally in a prompt with input