code: function updateExpression() {
    // Default colorizer will not color anything
    var nullColorizer = function(item) { return 0; }
  
    var input = $('.expression');
    var expression = input.val();
  
    var colorizer;
  
    if (!expression) {
      // No expression specified. Don't colorize anything.
      colorizer = nullColorizer;
      input.css('background-color', '#fff');
    } else {
      try {
        // Build highlighter from user's expression
        colorizer = compileExpression(expression); // <-- Filtrex!
        input.css('background-color', '#dfd');
      } catch (e) {
        // Failed to parse expression. Don't highlight anything.
        colorizer = nullColorizer;
        input.css('background-color', '#fdd');
      }
    }
  
    colorizeRows(colorizer);
  }
docs: When user entered expression changes, attempt to parse it
  and colorize rows based on expression.