Empty line in ace editor shows "x" mark in custom mode

Question

I already worked on the following ticket How to integrate syntax check in Ace Editor using custom mode?

I want to build the custom mode for ace editor (i.e every lines must contains semi colon except empty lines), so I created worker and mode based on above ticket, but now the issue is "missing semicolon" error shown for empty lines

consider the example:

1. In the ace editor, type in a query1, query2 in line 1 and line 2 respectively
2. Leave the third line blank
3. Now in fourth line, type a query without semicolon in the end, x mark appears in third line 4 And when the fifth line is also without a semicolon, then the x mark is displayed at fourth query

In the image "X" mark is shown for wrong line, How do I fix it?

Answer 1

To not show error for empty strings you need to continue loop in the case if lastLineCharacter is empty. So instead of

     if (lastLineCharacter === ';')
         continue;

use

     if (!lastLineCharacter || lastLineCharacter === ';')
         continue;

or use a regexp

     if (/[^;\s]\s*$/.test(lines[i]))
         continue;

Here's a complete working example

define('ace/mode/javascript-custom', [], function(require, exports, module) {

  var oop = require("ace/lib/oop");
  var TextMode = require("ace/mode/text").Mode;
  var Tokenizer = require("ace/tokenizer").Tokenizer;
  var ExampleHighlightRules = require("ace/mode/example_highlight_rules").ExampleHighlightRules;

  var UIWorkerClient = require("ace/worker/worker_client").UIWorkerClient

  var Mode = function() {
    this.HighlightRules = ExampleHighlightRules;
  };
  oop.inherits(Mode, TextMode);

  (function() {
    this.lineCommentStart = "--";
    this.blockComment = {
      start: "->",
      end: "<-"
    };


    this.createWorker = function(session) {
      // use UiWorkerClient for the demo
      var worker = new UIWorkerClient(["ace"], "ace/mode/semicolonlineend_worker",
        "SemicolonLineEndCheckWorker");
      debugger
      worker.attachToDocument(session.getDocument());

      worker.on("annotate", function(results) {
        session.setAnnotations(results.data);
      });

      worker.on("terminate", function() {
        session.clearAnnotations();
      });

      return worker;
    };


  }).call(Mode.prototype);

  exports.Mode = Mode;
});

define('ace/mode/example_highlight_rules', [], function(require, exports, module) {
  var oop = require("ace/lib/oop");
  var TextHighlightRules = require("ace/mode/text_highlight_rules").TextHighlightRules;

  var ExampleHighlightRules = function() {

    var keywordMapper = this.createKeywordMapper({
      "variable.language": "this",
      "keyword": "one|two",
      "constant.language": "true|false|null"
    }, "text", true);

    this.$rules = {
      "start": [{
        token: "comment",
        regex: "->",
        next: [{
          regex: "<-",
          token: "comment",
          next: "start"
        }, {
          defaultToken: "comment"
        }]
      }, {
        regex: "\\w+\\b",
        token: keywordMapper
      }, {
        token: "comment",
        regex: "--.*"
      }, {
        token: "string",
        regex: '"',
        next: [{
          regex: /\\./,
          token: "escape.character"
        }, {
          regex: '"',
          token: "string",
          next: "start"
        }, {
          defaultToken: "string"
        }]
      }, {
        token: "numbers",
        regex: /\d+(?:[.](\d)*)?|[.]\d+/
      }]
    };
    this.normalizeRules()
  };

  oop.inherits(ExampleHighlightRules, TextHighlightRules);

  exports.ExampleHighlightRules = ExampleHighlightRules;

});

define("ace/mode/semicolonlineend_worker", [], function(require, exports, module) {
  "use strict";

  var oop = require("../lib/oop");
  var Mirror = require("../worker/mirror").Mirror;

  var SemicolonLineEndCheckWorker = exports.SemicolonLineEndCheckWorker = function(sender) {
    Mirror.call(this, sender);
    this.setTimeout(100);
  };

  oop.inherits(SemicolonLineEndCheckWorker, Mirror);

  (function() {

    this.onUpdate = function() {
      var lines = this.doc.getAllLines();
      var errors = [];

      for (var i = 0; i < lines.length; i++) {
        var lastLineCharacter = lines[i].trim().slice(-1);
        if (!lastLineCharacter || lastLineCharacter === ';')
          continue;

        errors.push({
          row: i,
          column: lines[i].length - 1,
          text: "Missing semicolon at the end of the line",
          type: "warning",
          raw: "Missing semicolon"
        });

      }

      this.sender.emit("annotate", errors);
    };

  }).call(SemicolonLineEndCheckWorker.prototype);

});


var langTools = ace.require("ace/ext/language_tools");
var editor = ace.edit("editor");

editor.session.setMode("ace/mode/javascript-custom");
editor.setOptions({
  enableBasicAutocompletion: true,
  enableLiveAutocompletion: true,
  theme: "ace/theme/xcode"
});

<script src="https://ajaxorg.github.io/ace-builds/src/ace.js"></script>

<!-- included only for demo -->
<script src="https://ajaxorg.github.io/ace-builds/src/worker-json.js"></script>

<script src="https://ajaxorg.github.io/ace-builds/src/ext-language_tools.js"></script>
<div id="editor" style="height: 200px; width: 400px">c d e; g
</div>
<div id="commandline" style="position: absolute; bottom: 10px; height: 20px; width: 800px;"></div>