Tryit Editor v2.7

Edit This Code:
<!DOCTYPE html>
<html>
<body>

<p>Click the button to check if all the answer values in the array is the same.</p>

<button onclick="myFunction()">Try it</button>

<p id="demo"></p>

<script>
var survey = [
    { name: "Steve",   answer: "Yes"},
    { name: "Jessica", answer: "Yes"},
    { name: "Peter",   answer: "Yes"},
    { name: "Elaine",  answer: "No"}
];

function isSameAnswer(el,index,arr) {
    // Do not test the first array element, as you have nothing to compare to
    if (index === 0){
        return true;
    }
    else {
    //do each array element value match the value of the previous array element
        return (el.answer === arr[index - 1].answer);
    }
}

function myFunction() {
    document.getElementById("demo").innerHTML = survey.every(isSameAnswer);
}
</script>

</body>
</html>