Selection-enhancer user-script

selection-enhancer.js

// ==UserScript==
// @name         Selection enhancer.
// @namespace    http://tampermonkey.net/
// @version      1.2
// @description  Control-click selects and extends-selection.
// @author       tukkek
// @match        *://*/*
// @grant        none
// ==/UserScript==
function expand(c){return c&&!/\s/.test(c)}

function select(x,y){
  let position=document.caretPositionFromPoint(x,y)
  if(!position) return false
  let range=document.createRange()
  range.setStart(position.offsetNode,position.offset)
  range.collapse(true)
  let node=range.startContainer
  if(!range||!node||node.nodeType!=Node.TEXT_NODE) return false
  let offset=range.startOffset
  let text=node.textContent
  if(!text) return false
  let start=offset
  while(start>0&&expand(text[start-1])) start-=1
  let end=offset
  while(end<text.length&&expand(text[end])) end+=1
  if(start==end) return false
  range.setStart(node,start)
  range.setEnd(node,end)
  return range
}

function click(event){
  if(!event.ctrlKey) return
  if(event.target.tagName=='A') return
  let range=select(event.clientX,event.clientY)
  if(!range) return
  let selection=window.getSelection()
  for(let i=0;i<selection.rangeCount;i+=1){
    let previous=selection.getRangeAt(i)
    if(!previous.toString().length) continue
    let start=previous.compareBoundaryPoints(Range.START_TO_START,range)
    if(start<0) range.setStart(previous.startContainer,previous.startOffset)
    let end=previous.compareBoundaryPoints(Range.END_TO_END,range)
    if(end>0) range.setEnd(previous.endContainer,previous.endOffset)
  }
  selection.empty()
  selection.addRange(range)
}

function press(event){if(event.key=='Escape') document.getSelection().empty()}

document.addEventListener('click',(event)=>click(event))
document.addEventListener('keyup',(event)=>press(event))