Custom Validators

Example of creating a custom validator using a custom function in expressions

                        function MyTextValidator(params) {
    var value = params[0];
    return value.indexOf("survey");
// Register the function for use in SurveyJS expressions
Survey.FunctionFactory.Instance.register("MyTextValidator", MyTextValidator);


var json = {
  "questions": [
      "type": "comment",
      "name": "memo",
      "isRequired": true,
      "title": "Type here 'survey' to pass the validation ",
      "validators": [
          "type": "expression",
          "text": "You text should contains 'survey' word.",
          "expression": "MyTextValidator({memo}) >= 0"

window.survey = new Survey.Model(json);

    survey.onComplete.add(function(result) {
        document.querySelector('#surveyResult').textContent =
            "Result JSON:\n" + JSON.stringify(, null, 3);

ReactDOM.render(<Survey.Survey model={survey}  />, document.getElementById("surveyElement"));

<!DOCTYPE html>
    <title>Example of creating a custom validator using a custom function in expressions, Reactjs Survey Library Example</title>

    <meta name="viewport" content="width=device-width, initial-scale=1">
    <script src=""></script>
    <script src=""></script>
    <script src=""></script>
    <script src=""></script>
<script src=""></script>
<link href="" type="text/css" rel="stylesheet" />
    <link rel="stylesheet" href="./index.css">

                <div id="surveyElement">
    <div id="surveyResult"></div>

<script type="text/babel" src="./index.js"></script>