Run Expression Trigger


function setOfficialCountryName(params) {
    if (params.length < 2)
    var country = params[0];
    var officialName = params[1];
    var survey = this.survey;
    if (!country || !country.length) {
    survey.setVariable("request_processing", true);
    survey.setVariable("request_error", null);
    country = country
        .toUpperCase() + country
        url: "" + country,
        type: "GET",
        success: function (data) {
            if (!!data && data.length > 0) {
                var countryValue = data[0];
                survey.setValue(officialName, countryValue.officialName);
                survey.setVariable("hasError", false);
            } else {
                survey.setVariable("hasError", true);
                survey.setVariable("request_error", "The country is not found.");
                survey.setVariable("request_processing", false);
        error: function (xhr, ajaxOptions, thrownError) {
            survey.setVariable("hasError", true);
            survey.setVariable("request_error", "The country is not found.");

Survey.FunctionFactory.Instance.register("setOfficialCountryName", setOfficialCountryName);

                    var json = {
  "elements": [
      "type": "text",
      "name": "country",
      "title": "Please enter the country"
      "type": "html",
      "name": "requesting",
      "html": "The data is requesting",
      "visibleIf": "{request_processing} = true"
      "type": "text",
      "name": "name_official",
      "title": "Official name is:",
      "readOnly": true,
      "visibleIf": "{name_official} notempty"
      "type": "html",
      "name": "error",
      "html": "The following error has happened: <b>{request_error}</b>",
      "visibleIf": "{hasError} = true"
  "triggers": [
      "type": "runexpression",
      "expression": "{country} notempty or {country} empty",
      "runExpression": "setOfficialCountryName({country}, 'name_official')"

                    window.survey = new Survey.Model(json);
            survey.onComplete.add(function(sender) {
            document.querySelector('#surveyResult').textContent =
            "Result JSON:\n" + JSON.stringify(, null, 3);
                ko.applyBindings({ model: survey }, document.getElementById("surveyElement"));

<!DOCTYPE html>
<html lang="en">
    <title>Run Expression Trigger, Knockoutjs Survey Library Example</title>
<meta name="viewport" content="width=device-width" />
    <script src=""></script>
    <script src=""></script>
    <script src="/DevBuilds/survey-core/survey.core.min.js"></script>
    <script src="/DevBuilds/survey-core/survey.i18n.min.js"></script>
    <script src="/DevBuilds/survey-knockout-ui/survey-knockout-ui.min.js"></script>
    <link href="/DevBuilds/survey-core/defaultV2.min.css" type="text/css" rel="stylesheet" />
    <link rel="stylesheet" href="./index.css">

<body style="margin: 0">
            <div id="surveyElement" style="display:inline-block;width:100%;">
                    <survey params="survey: model"></survey>
    <div id="surveyResult"></div>

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

Sorry, we can't retrieve the data from server. Please comeback later.

Why we use cookies.

This site uses cookies to make your browsing experience more convenient and personal. Cookies store useful information on your computer to help us improve the efficiency and relevance of our site for you. In some cases, they are essential to making the site work properly. By accessing this site, you consent to the use of cookies.

For more information, refer to DevSoft Baltic’ privacy policy and cookie policy.