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JavaScript JavaScript Loops, Arrays and Objects Tracking Multiple Items with Arrays Build a Quiz Challenge, Part 1

Posted by Mihai-Ady Zvancu
Mihai-Ady Zvancu
7,657 Points

Why does my .toLowerCase() function NOT work inside the for loop?

The .toLowerCase() function in the following code is not working? Why is this happening?

function print(message) { document.write(message); }

let qa = [ ["What is the speed of light (in km/s)?","300000"], ["What is the third closest planet to the Sun?","earth"], ["When did the Second World War end","1945"]
];

let html_1 = "; let html_2 = "; let corr_ans = 0; let answer;

for (let i = 0; i<qa.length; i++){

answer = prompt (qa[i][0]);

answer.toLowerCase();

console.log(answer); // I have put this line of code to see if .toLowerCase() function works

if (answer === qa[i][1]){
html_1 += "<li>"+qa[i][0]+"</li>";
corr_ans++; }else{ html_2 += "<li>"+qa[i][0]+"</li>"; }

}

print("<h2>You answered "+corr_ans+" question(s) correctly!");

print("<ol>Questions with correct answer: "+html_1+"</ol>")

print("<ol>Questions with incorrect answer: "+html_2+"</ol>");

2 Answers

Zimri Leijen
Zimri Leijen
11,835 Points

Note: The toLowerCase() method does not change the original string.

Basically, toLowerCase() makes a lowercase COPY of the string.

If you don't overwrite the original string with the copy, or use the copy somewhere, then it doesn't really do anything.

So instead of

answer.toLowerCase()

you can do

answer = answer.toLowerCase()

// alternatively
const lowerCaseAnswer = answer.toLowerCase();
Mihai-Ady Zvancu
Mihai-Ady Zvancu
7,657 Points
Mihai-Ady Zvancu
Mihai-Ady Zvancu
7,657 Points

Thank you, all!