curriculum/challenges/english/blocks/learn-advanced-array-methods-by-building-a-statistics-calculator/635080d80b72803e973841da.md
Like the other methods, .reduce() takes a callback. This callback, however, takes at least two parameters. The first is the <dfn>accumulator</dfn>, and the second is the current element in the array. The return value for the callback becomes the value of the accumulator on the next iteration.
array.reduce((acc, el) => {
});
For your sum variable, pass a callback to .reduce() that takes the accumulator and the current element as parameters. The callback should return the sum of the accumulator and the current element.
Your reduce method should have a callback function which takes an acc and an el parameters.
assert.match(getMean.toString(), /(array\.reduce\(\s*\(\s*acc\s*,\s*el\s*\)\s*=>|array\.reduce\(\s*function\s*\(\s*acc\s*,\s*el\s*\)\s*\{)/)
Your reduce method should return the sum of acc and el.
assert.match(getMean.toString(), /(array\.reduce\(\s*\(\s*acc\s*,\s*el\s*\)\s*=>|array\.reduce\(\s*function\s*\(\s*acc\s*,\s*el\s*\)\s*\{)\s*(return\s+)?\s*acc\s*\+\s*el/)
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1" />
<link rel="stylesheet" href="./styles.css" />
<script src="./script.js"></script>
<title>Statistics Calculator</title>
</head>
<body>
<h1>Statistics Calculator</h1>
<p>Enter a list of comma-separated numbers.</p>
<form onsubmit="calculate();">
<label for="numbers">Numbers:</label>
<input type="text" name="numbers" id="numbers" />
<button type="submit">Calculate</button>
</form>
<div class="results">
<p>
The <dfn>mean</dfn> of a list of numbers is the average, calculated by
taking the sum of all numbers and dividing that by the count of numbers.
</p>
<p class="bold">Mean: <span id="mean"></span></p>
<p>
The <dfn>median</dfn> of a list of numbers is the number that appears in
the middle of the list, when sorted from least to greatest.
</p>
<p class="bold">Median: <span id="median"></span></p>
<p>
The <dfn>mode</dfn> of a list of numbers is the number that appears most
often in the list.
</p>
<p class="bold">Mode: <span id="mode"></span></p>
<p>
The <dfn>range</dfn> of a list of numbers is the difference between the
largest and smallest numbers in the list.
</p>
<p class="bold">Range: <span id="range"></span></p>
<p>
The <dfn>variance</dfn> of a list of numbers measures how far the values
are from the mean, on average.
</p>
<p class="bold">Variance: <span id="variance"></span></p>
<p>
The <dfn>standard deviation</dfn> of a list of numbers is the square
root of the variance.
</p>
<p class="bold">
Standard Deviation: <span id="standardDeviation"></span>
</p>
</div>
</body>
</html>
body {
margin: 0;
background-color: rgb(27, 27, 50);
text-align: center;
color: #fff;
}
button {
cursor: pointer;
background-color: rgb(59, 59, 79);
border: 3px solid white;
color: white;
}
input {
background-color: rgb(10, 10, 35);
color: white;
border: 1px solid rgb(59, 59, 79);
}
.bold {
font-weight: bold;
}
--fcc-editable-region--
const getMean = (array) => {
const sum = array.reduce();
}
--fcc-editable-region--
const calculate = () => {
const value = document.querySelector("#numbers").value;
const array = value.split(/,\s*/g);
const numbers = array.map(el => Number(el)).filter(el => !isNaN(el));
}