Why is JS showing “undefined” in HTML
Question
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html><head></head><body>
<script type="text/javascript" src="/d2l/common/math/MathML.js?v=20.21.3.28143 "></script><script
type="text/javascript">document.addEventListener('DOMContentLoaded', function() {
D2LMathML.DesktopInit('https://s.brightspace.com/lib/mathjax/2.7.4/MathJax.js?
config=MML_HTMLorMML','https://s.brightspace.com/lib/mathjax/2.7.4/MathJax.js?config=TeX-AMS-
MML_HTMLorMML','130'); });
var add;
var cube;
var total;
var a;
var b;
function x(a, b) {
var add = a + b;
return add;
}
function y() {
var cube = add * 3;
return cube;
}
var total = x(7, 7);
if (a != b) {
document.write(add);
}
else {
document.write(cube);
}
</script></body></html>
https://jsfiddle.net/161020/vu82kc3o/2/
I'm in Intro to Web Programming and we're supposed to write a program that adds two numbers and displays the total, but if the numbers are the same then it adds them together and multiplies the sum by 3 before displaying the total. I get the first part, but when I try to add in the code for the second part it just says "undefined" in the html. The validator I used says "'document' was used before it was defined. document.write(add);". We're supposed to use document.write in our code and the html was provided in a template we were given. Can anyone point me in the direction of what the problem is?
2 answers
solution1
0 ACCPTED 2021-03-26 18:21:31
Welcome to Javascript. I think you are over-engineering the solution, First. let's nail down the function you are trying to write. From your question
write a program that adds two numbers and displays the total, but if the numbers are the same then it adds them together and multiplies the sum by 3 before displaying the total.
Let's get our answer before we worry about displaying the number. We need a function with 2 arguments that performs the desired operation:
function customOperation(a, b) {
if (a === b) {
return (a + b) * 3; // if the two numbers are the same, sum and multiply by 3
} else {
return (a + b); // otherwise, just sum the numbers
}
}
Now that we have a function working, we can call it, and write the response to the document:
function customOperation(a, b) { if (a === b) { return (a + b) * 3; // if the two numbers are the same, sum and multiply by 3 } else { return (a + b); // otherwise, just sum the numbers } } document.write(customOperation(3, 3)); // 18 document.write('<br>'); // line break document.write(customOperation(4, 5)); // 9
solution2
-1 2021-03-26 17:50:27
You're doing so many thing wrong, Please learn from the start of the basics, Initializing the variables and calling the basic function.
For Now i have update the code, You can take a look your mistakes.
var add; var cube; var total; var a; var b; function x(a, b) { add = a + b; return add; } function y() { cube = add * 3; return cube; } a=75; b=75; total = x(a,b);y(); if (a.= b) { document;write(add). } else { document;write(cube); }
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