I just finished an algebra course in high school, and decided to create a program that would take 3 values and do some calculations to give me a z-value. However, when trying to gather the information, I keep getting an error saying that it cannot read property 'value' of null. I've looked through this site, but couldn't implement a fix. Right now the code is just supposed to console.log the values put in, along with the z-score, determined by an equation in the code.
// z = (x-μ)/σ
var textboxD;
var textboxM;
var textboxS;
var zScore;
function calculateZ() {
var textboxD = document.getElementById("stardardD").value
var textboxM = document.getElementById("mean").value
var textboxS = document.getElementById("score").value
var zScore = (textboxS - textboxM) / textboxD
console.log(textboxD + ", " + textboxM + ", " + textboxS + ", " + zScore);
}<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
</head>
<body>
<input id="standardD"type="text"/>
σ
<input id="mean"type="text"/>
μ
<input id="score"type="text"/>
score
<br>
<button onClick="calculateZ()">
CALCULATE
</button>
</body>
</html>
