var jsCode = [ '"use strict";', 'function Person(age) {', ' if (age) {', ' this.age = age;', ' }', '}', 'Person.prototype.getAge = function () {', ' return this.age;', '};' ].join('\n'); var editor = monaco.editor.create(document.getElementById('container'), { value: jsCode, language: 'javascript', glyphMargin: true }); var decorations = editor.deltaDecorations( [], [ { range: new monaco.Range(3, 1, 3, 1), options: { isWholeLine: true, className: 'myContentClass', glyphMarginClassName: 'myGlyphMarginClass' } } ] ); // You can now use `decorations` to change or remove the decoration