Write an expression in 'visibleIf' to show/hide your question(s)

Source code: Survey setup
Survey.defaultBootstrapCss.navigationButton = "btn btn-primary";
Survey.Survey.cssType = "bootstrap";
var survey = new Survey.Model({ showQuestionNumbers: "off",
     questions: [
    { type: "radiogroup", name: "haveKids", title: "Do you have a kid(s)?", isRequired: true, choices:["Yes", "No"], colCount: 0},
    { type: "dropdown", name: "kids", title: "How many kids do you have", visibleIf: "{haveKids}='Yes'",
        isRequired: true, choices:[1, 2, 3, 4, 5] }, 
    { type: "dropdown", name: "kid1Age", title: "The first kid age:", visibleIf: "{haveKids}='Yes' and {kids} >= 1",
        isRequired: true, choices:[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]},
    { type: "dropdown", name: "kid2Age", title: "The second kid age:", visibleIf: "{haveKids}='Yes' and {kids} >= 2",
        isRequired: true, startWithNewLine: false, choices:[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]},
    { type: "dropdown", name: "kid3Age", title: "The third kid age:", visibleIf: "{haveKids}='Yes' and {kids} >= 3",
        isRequired: true, startWithNewLine: false, choices:[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]},
    { type: "dropdown", name: "kid4Age", title: "The fourth kid age:", visibleIf: "{haveKids}='Yes' and {kids} >= 4",
        isRequired: true, startWithNewLine: false, choices:[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]},
    { type: "dropdown", name: "kid5Age", title: "The fifth kid age:", visibleIf: "{haveKids}='Yes' and {kids} >= 5",
        isRequired: true, startWithNewLine: false, choices:[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]}
]});

var app = new Vue({
    el: '#surveyElement',
    data: {
        survey: survey
    }
});

clearInvisibleValues : Clear values for invsible questions on survey complete, default is false.

survey.clearInvisibleValues = yourValue; survey.render();