Check null value in a quiz - vue.js

Question

I did a quiz with vue.js and i would like to check if a value is null before put it in the console.log. I Can't find how to do that...
I have a lot of questions to put in this quiz but some of them just need to be ignored in the final result. I just want to bypass all the questions with value:null.
"use strict";
window.onload = function() {
var quiz = {
title: 'Quizz',
questions: [{
text: "Question 1",
responses: [{
text: 'a',
value: null,
},
{
text: 'b',
value: null,
}
]
},
{
text: "Question 2",
responses: [{
text: 'a',
value: '1',
},
{
text: 'b',
value: '2',
}
]
}
]
};
var app = new Vue({
el: '#app',
data: {
quiz: quiz,
questionIndex: 0,
userResponses: Array(),
show: true
},
methods: {
// Go to next question
next: function() {
console.log(this.userResponses);
this.questionIndex++;
},
// Go to previous question
prev: function() {
this.questionIndex--;
},
score: function() {
//find the highest occurence in responses
var userResponses = Array.prototype.concat.apply([], this.userResponses);
var modeMap = {};
var maxEl = userResponses,
maxCount = 1;
for (var i = 0; i < userResponses.length; i++) {
var el = userResponses[i];
if (modeMap[el] == null)
modeMap[el] = 1;
else
modeMap[el]++;
if (modeMap[el] > maxCount) {
maxEl = el;
maxCount = modeMap[el];
}
}
return maxEl;
}
}
});
}

Answer 1

I find it, just add : var userResponses = this.userResponses.filter(Boolean);