extension.js

// Highlight non breakable spaces and other similar non-ascii characters, also highlights trailing whitespace
// Based on my sublime extension: https://github.com/possan/sublime_unicode_nbsp/blob/master/sublime_unicode_nbsp.py

var vscode = require('vscode')

const MAX_DOCUMENT_SIZE = 1048576

var INVALID_INLINE_CHARS = [
  '\\x82', // High code comma
  '\\x84', // High code double comma
  '\\x85', // Tripple dot
  '\\x88', // High carat
  '\\x91', // Forward single quote
  '\\x92', // Reverse single quote
  '\\x93', // Forward double quote
  '\\x94', // Reverse double quote
  '\\x95',
  '\\x96', // High hyphen
  '\\x97', // Double hyphen
  '\\x99',
  '\\xa0',
  '\\xa6', // Split vertical bar
  '\\xab', // Double less than
  '\\xbb', // Double greater than
  '\\xbc', // one quarter
  '\\xbd', // one half
  '\\xbe', // three quarters
  '\\xbf', // c-single quote
  '\\xa8', // modifier - under curve
  '\\xb1'  // modifier - under line
]

var INVALID_TRAILING_CHARS = [
  '\\x95',
  '\\x99',
  '\\xa0',
  '\\xa8', // modifier - under curve
  '\\xb1', // modifier - under line
  '\\t',
  '\\r',
  ' '
]

exports.activate = function(context) {
  const whitespaceDecorationType = vscode.window.createTextEditorDecorationType({
    backgroundColor: 'rgba(255,80,0,0.75)'
  })

  vscode.window.onDidChangeActiveTextEditor(editor => {
    activeEditor = editor
    if (editor) {
      triggerUpdateDecorations()
    }
  }, null, context.subscriptions)

  vscode.workspace.onDidChangeTextDocument(event => {
    if (activeEditor && event.document === activeEditor.document) {
      triggerUpdateDecorations();
    }
  }, null, context.subscriptions);

  var timeout = null;

  function triggerUpdateDecorations() {
    if (timeout) {
      clearTimeout(timeout);
    }
    timeout = setTimeout(updateDecorations, 500);
  }

  const re1 = new RegExp('[' + INVALID_INLINE_CHARS.join('') + ']+', 'g')
  const re2 = new RegExp('[' + INVALID_TRAILING_CHARS.join('') + ']+$', 'img')

  function updateDecorations() {
    if (!activeEditor) {
      return;
    }

    if (activeEditor.document.length > MAX_DOCUMENT_SIZE) {
        return;
    }

    const text = activeEditor.document.getText()
    const decorations = []
    let match

    while (match = re1.exec(text)) {
      const startPos = activeEditor.document.positionAt(match.index)
      const endPos = activeEditor.document.positionAt(match.index + match[0].length)
      const decoration = { range: new vscode.Range(startPos, endPos), hoverMessage: 'Suspicious inline whitespace' }
      decorations.push(decoration)
    }

    while (match = re2.exec(text)) {
      const startPos = activeEditor.document.positionAt(match.index)
      const endPos = activeEditor.document.positionAt(match.index + match[0].length)
      const decoration = { range: new vscode.Range(startPos, endPos), hoverMessage: 'Suspicious trailing whitespace' }
      decorations.push(decoration)
    }

    activeEditor.setDecorations(whitespaceDecorationType, decorations)
  }

  let activeEditor = vscode.window.activeTextEditor
  if (activeEditor) {
    triggerUpdateDecorations()
  }
}


exports.deactivate = function() {};