Calculate expression based on other answers - Expression question, jQuery Survey Library Example

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        <title>Calculate expression based on other answers - Expression question, jQuery Survey Library Example</title>
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        <link rel="stylesheet" href="./index.css">

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

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

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var json = {
    "showQuestionNumbers": "off",
    "elements": [
      {
        type: "matrix",
        name: "Quality",
        title: "Please score each department below.",
        columns: [{
          value: 0,
          text: "None"
        }, {
          value: 25,
          text: "Isolated"
        }, {
          value: 50,
          text: "Some"
        }, {
          value: 100,
          text: "Widespread"
        }],
        rows: [{
          value: "training",
          text: "Training"
        }, {
          value: "support",
          text: "Support"
        }, {
          value: "safety",
          text: "Safety"
        }, {
          value: "communication",
          text: "Communication"
        }]
      }, {
          "type": "expression",
          "name": "total",
          "title": "Total Quality:",
          "expression": "sumInObject({Quality})",
          "displayStyle": "decimal",
          "startWithNewLine": true
      }
    ]
};

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

survey
    .onComplete
    .add(function (result) {
        document
            .querySelector('#surveyResult')
            .innerHTML = "result: " + JSON.stringify(result.data);
    });
    
function sumInObject(params) {
  if (params.length != 1) return 0;
  if(!params[0]) return 0;
  const object = params[0];
  const array = Object.keys(object)
    .map(key => object[key])
    .map(value => parseInt(value));
  return array.reduce((left, right) => left + right);
}

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

$("#surveyElement").Survey({model: survey});