--- id: 63508750f040a348a440a0bf title: Step 17 challengeType: 0 dashedName: step-17 --- # --description-- To display the value of `mean`, your app has a `#mean` element ready to go. Use a `.querySelector` to find that element, and then set its `.textContent` to the value of `mean`. # --hints-- Your `calculate` function should use a `document.querySelector()`. ```js assert.lengthOf(calculate.toString().match(/document\.querySelector\(/g), 2); ``` Your `.querySelector()` should target the `#mean` element. ```js assert.match(calculate.toString(), /document\.querySelector\(\s*('|")#mean\1\s*\)/); ``` Your `calculate` function should set the `#mean` element's `.textContent` to the value of `mean`. ```js assert.match(calculate.toString(), /document\.querySelector\(\s*('|")#mean\1\s*\)\s*\.textContent\s*=\s*mean\s*;?/); ``` # --seed-- ## --seed-contents-- ```html Statistics Calculator

Statistics Calculator

Enter a list of comma-separated numbers.

The mean of a list of numbers is the average, calculated by taking the sum of all numbers and dividing that by the count of numbers.

Mean:

The median of a list of numbers is the number that appears in the middle of the list, when sorted from least to greatest.

Median:

The mode of a list of numbers is the number that appears most often in the list.

Mode:

The range of a list of numbers is the difference between the largest and smallest numbers in the list.

Range:

The variance of a list of numbers measures how far the values are from the mean, on average.

Variance:

The standard deviation of a list of numbers is the square root of the variance.

Standard Deviation:

``` ```css 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; } ``` ```js const getMean = (array) => array.reduce((acc, el) => acc + el, 0) / array.length; --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)); const mean = getMean(numbers); } --fcc-editable-region-- ```