freeCodeCamp/curriculum/challenges/english/15-javascript-algorithms-and-data-structures-22/learn-functional-programming-by-building-a-spreadsheet/646d4717a689e1cfa232e357.md

id, title, challengeType, dashedName

id	title	challengeType	dashedName
646d4717a689e1cfa232e357	Step 92	0	step-92

--description--

Like you did with your highPrecedence() function, your evalFormula() function needs to ensure it has evaluated and replaced everything.

Use a ternary to check if functionExpanded is equal to the original string x. If it is, return functionExpanded, otherwise return the result of calling evalFormula() again with functionExpanded and cells as arguments.

--hints--

Your evalFormula function should use the return keyword.

assert.match(code, /const\s+evalFormula\s*=\s*\(\s*x\s*,\s*cells\s*\)\s*=>\s*{\s*const\s+idToText\s*=\s*(\(\s*id\s*\)|id)\s*=>\s*cells\.find\(\s*(\(\s*cell\s*\)|cell)\s*=>\s*(?:cell\.id\s*===\s*id|id\s*===\s*cell\.id)\s*\)\.value\s*;?\s*const\s+rangeRegex\s*=\s*\/\(\[A-J\]\)\(\[1-9\]\[0-9\]\?\):\(\[A-J\]\)\(\[1-9\]\[0-9\]\?\)\/(gi|ig)\s*;?\s*const\s+rangeFromString\s*=\s*\(\s*num1\s*,\s*num2\s*\)\s*=>\s*range\(\s*parseInt\(\s*num1\s*\)\s*,\s*parseInt\(\s*num2\s*\)\s*\)\s*;?\s*const\s+elemValue\s*=\s*(\(\s*num\s*\)|num)\s*=>\s*(\(\s*character\s*\)|character)\s*=>\s*idToText\(\s*character\s*\+\s*num\s*\)\s*;?\s*const\s+addCharacters\s*=\s*(\(\s*character1\s*\)|character1)\s*=>\s*(\(\s*character2\s*\)|character2)\s*=>\s*(\(\s*num\s*\)|num)\s*=>\s*charRange\(\s*character1\s*,\s*character2\s*\)\.map\(\s*elemValue\(\s*num\s*\)\s*\)\s*;?\s*const\s+rangeExpanded\s*=\s*x\.replace\(\s*rangeRegex\s*,\s*\(\s*_match\s*,\s*char1\s*,\s*num1\s*,\s*char2\s*,\s*num2\s*\)\s*=>\s*rangeFromString\(\s*num1\s*,\s*num2\s*\)\.map\(\s*addCharacters\s*\(\s*char1\s*\)\(\s*char2\s*\)\s*\)\s*\)\s*;?\s*const\s+cellRegex\s*=\s*\/\[A-J\]\[1-9\]\[0-9\]\?\/(gi|ig)\s*;?\s*const\s+cellExpanded\s*=\s*rangeExpanded\.replace\(\s*cellRegex\s*,\s*(\(\s*match\s*\)|match)\s*=>\s*idToText\(\s*match\.toUpperCase\(\s*\)\s*\)\s*\)\s*;?\s*(?:const|let|var)\s+functionExpanded\s*=\s*applyFunction\(\s*cellExpanded\s*\)\s*;?\s*return/);

Your return statement should check if functionExpanded is equal to x.

assert.match(code, /const\s+evalFormula\s*=\s*\(\s*x\s*,\s*cells\s*\)\s*=>\s*{\s*const\s+idToText\s*=\s*(\(\s*id\s*\)|id)\s*=>\s*cells\.find\(\s*(\(\s*cell\s*\)|cell)\s*=>\s*(?:cell\.id\s*===\s*id|id\s*===\s*cell\.id)\s*\)\.value\s*;?\s*const\s+rangeRegex\s*=\s*\/\(\[A-J\]\)\(\[1-9\]\[0-9\]\?\):\(\[A-J\]\)\(\[1-9\]\[0-9\]\?\)\/(gi|ig)\s*;?\s*const\s+rangeFromString\s*=\s*\(\s*num1\s*,\s*num2\s*\)\s*=>\s*range\(\s*parseInt\(\s*num1\s*\)\s*,\s*parseInt\(\s*num2\s*\)\s*\)\s*;?\s*const\s+elemValue\s*=\s*(\(\s*num\s*\)|num)\s*=>\s*(\(\s*character\s*\)|character)\s*=>\s*idToText\(\s*character\s*\+\s*num\s*\)\s*;?\s*const\s+addCharacters\s*=\s*(\(\s*character1\s*\)|character1)\s*=>\s*(\(\s*character2\s*\)|character2)\s*=>\s*(\(\s*num\s*\)|num)\s*=>\s*charRange\(\s*character1\s*,\s*character2\s*\)\.map\(\s*elemValue\(\s*num\s*\)\s*\)\s*;?\s*const\s+rangeExpanded\s*=\s*x\.replace\(\s*rangeRegex\s*,\s*\(\s*_match\s*,\s*char1\s*,\s*num1\s*,\s*char2\s*,\s*num2\s*\)\s*=>\s*rangeFromString\(\s*num1\s*,\s*num2\s*\)\.map\(\s*addCharacters\s*\(\s*char1\s*\)\(\s*char2\s*\)\s*\)\s*\)\s*;?\s*const\s+cellRegex\s*=\s*\/\[A-J\]\[1-9\]\[0-9\]\?\/(gi|ig)\s*;?\s*const\s+cellExpanded\s*=\s*rangeExpanded\.replace\(\s*cellRegex\s*,\s*(\(\s*match\s*\)|match)\s*=>\s*idToText\(\s*match\.toUpperCase\(\s*\)\s*\)\s*\)\s*;?\s*(?:const|let|var)\s+functionExpanded\s*=\s*applyFunction\(\s*cellExpanded\s*\)\s*;?\s*return\s+(?:functionExpanded\s*===\s*x|x\s*===\s*functionExpanded)/);

Your return statement should use a ternary operator.

assert.match(code, /const\s+evalFormula\s*=\s*\(\s*x\s*,\s*cells\s*\)\s*=>\s*{\s*const\s+idToText\s*=\s*(\(\s*id\s*\)|id)\s*=>\s*cells\.find\(\s*(\(\s*cell\s*\)|cell)\s*=>\s*(?:cell\.id\s*===\s*id|id\s*===\s*cell\.id)\s*\)\.value\s*;?\s*const\s+rangeRegex\s*=\s*\/\(\[A-J\]\)\(\[1-9\]\[0-9\]\?\):\(\[A-J\]\)\(\[1-9\]\[0-9\]\?\)\/(gi|ig)\s*;?\s*const\s+rangeFromString\s*=\s*\(\s*num1\s*,\s*num2\s*\)\s*=>\s*range\(\s*parseInt\(\s*num1\s*\)\s*,\s*parseInt\(\s*num2\s*\)\s*\)\s*;?\s*const\s+elemValue\s*=\s*(\(\s*num\s*\)|num)\s*=>\s*(\(\s*character\s*\)|character)\s*=>\s*idToText\(\s*character\s*\+\s*num\s*\)\s*;?\s*const\s+addCharacters\s*=\s*(\(\s*character1\s*\)|character1)\s*=>\s*(\(\s*character2\s*\)|character2)\s*=>\s*(\(\s*num\s*\)|num)\s*=>\s*charRange\(\s*character1\s*,\s*character2\s*\)\.map\(\s*elemValue\(\s*num\s*\)\s*\)\s*;?\s*const\s+rangeExpanded\s*=\s*x\.replace\(\s*rangeRegex\s*,\s*\(\s*_match\s*,\s*char1\s*,\s*num1\s*,\s*char2\s*,\s*num2\s*\)\s*=>\s*rangeFromString\(\s*num1\s*,\s*num2\s*\)\.map\(\s*addCharacters\s*\(\s*char1\s*\)\(\s*char2\s*\)\s*\)\s*\)\s*;?\s*const\s+cellRegex\s*=\s*\/\[A-J\]\[1-9\]\[0-9\]\?\/(gi|ig)\s*;?\s*const\s+cellExpanded\s*=\s*rangeExpanded\.replace\(\s*cellRegex\s*,\s*(\(\s*match\s*\)|match)\s*=>\s*idToText\(\s*match\.toUpperCase\(\s*\)\s*\)\s*\)\s*;?\s*(?:const|let|var)\s+functionExpanded\s*=\s*applyFunction\(\s*cellExpanded\s*\)\s*;?\s*return\s+(?:functionExpanded\s*===\s*x|x\s*===\s*functionExpanded)\s*\?/);

If the ternary condition is true, your evalFormula() should return functionExpanded.

assert.match(code, /const\s+evalFormula\s*=\s*\(\s*x\s*,\s*cells\s*\)\s*=>\s*{\s*const\s+idToText\s*=\s*(\(\s*id\s*\)|id)\s*=>\s*cells\.find\(\s*(\(\s*cell\s*\)|cell)\s*=>\s*(?:cell\.id\s*===\s*id|id\s*===\s*cell\.id)\s*\)\.value\s*;?\s*const\s+rangeRegex\s*=\s*\/\(\[A-J\]\)\(\[1-9\]\[0-9\]\?\):\(\[A-J\]\)\(\[1-9\]\[0-9\]\?\)\/(gi|ig)\s*;?\s*const\s+rangeFromString\s*=\s*\(\s*num1\s*,\s*num2\s*\)\s*=>\s*range\(\s*parseInt\(\s*num1\s*\)\s*,\s*parseInt\(\s*num2\s*\)\s*\)\s*;?\s*const\s+elemValue\s*=\s*(\(\s*num\s*\)|num)\s*=>\s*(\(\s*character\s*\)|character)\s*=>\s*idToText\(\s*character\s*\+\s*num\s*\)\s*;?\s*const\s+addCharacters\s*=\s*(\(\s*character1\s*\)|character1)\s*=>\s*(\(\s*character2\s*\)|character2)\s*=>\s*(\(\s*num\s*\)|num)\s*=>\s*charRange\(\s*character1\s*,\s*character2\s*\)\.map\(\s*elemValue\(\s*num\s*\)\s*\)\s*;?\s*const\s+rangeExpanded\s*=\s*x\.replace\(\s*rangeRegex\s*,\s*\(\s*_match\s*,\s*char1\s*,\s*num1\s*,\s*char2\s*,\s*num2\s*\)\s*=>\s*rangeFromString\(\s*num1\s*,\s*num2\s*\)\.map\(\s*addCharacters\s*\(\s*char1\s*\)\(\s*char2\s*\)\s*\)\s*\)\s*;?\s*const\s+cellRegex\s*=\s*\/\[A-J\]\[1-9\]\[0-9\]\?\/(gi|ig)\s*;?\s*const\s+cellExpanded\s*=\s*rangeExpanded\.replace\(\s*cellRegex\s*,\s*(\(\s*match\s*\)|match)\s*=>\s*idToText\(\s*match\.toUpperCase\(\s*\)\s*\)\s*\)\s*;?\s*(?:const|let|var)\s+functionExpanded\s*=\s*applyFunction\(\s*cellExpanded\s*\)\s*;?\s*return\s+(?:functionExpanded\s*===\s*x|x\s*===\s*functionExpanded)\s*\?\s*functionExpanded/);

If the ternary condition is false, your evalFormula() should return the result of calling evalFormula().

assert.match(code, /const\s+evalFormula\s*=\s*\(\s*x\s*,\s*cells\s*\)\s*=>\s*{\s*const\s+idToText\s*=\s*(\(\s*id\s*\)|id)\s*=>\s*cells\.find\(\s*(\(\s*cell\s*\)|cell)\s*=>\s*(?:cell\.id\s*===\s*id|id\s*===\s*cell\.id)\s*\)\.value\s*;?\s*const\s+rangeRegex\s*=\s*\/\(\[A-J\]\)\(\[1-9\]\[0-9\]\?\):\(\[A-J\]\)\(\[1-9\]\[0-9\]\?\)\/(gi|ig)\s*;?\s*const\s+rangeFromString\s*=\s*\(\s*num1\s*,\s*num2\s*\)\s*=>\s*range\(\s*parseInt\(\s*num1\s*\)\s*,\s*parseInt\(\s*num2\s*\)\s*\)\s*;?\s*const\s+elemValue\s*=\s*(\(\s*num\s*\)|num)\s*=>\s*(\(\s*character\s*\)|character)\s*=>\s*idToText\(\s*character\s*\+\s*num\s*\)\s*;?\s*const\s+addCharacters\s*=\s*(\(\s*character1\s*\)|character1)\s*=>\s*(\(\s*character2\s*\)|character2)\s*=>\s*(\(\s*num\s*\)|num)\s*=>\s*charRange\(\s*character1\s*,\s*character2\s*\)\.map\(\s*elemValue\(\s*num\s*\)\s*\)\s*;?\s*const\s+rangeExpanded\s*=\s*x\.replace\(\s*rangeRegex\s*,\s*\(\s*_match\s*,\s*char1\s*,\s*num1\s*,\s*char2\s*,\s*num2\s*\)\s*=>\s*rangeFromString\(\s*num1\s*,\s*num2\s*\)\.map\(\s*addCharacters\s*\(\s*char1\s*\)\(\s*char2\s*\)\s*\)\s*\)\s*;?\s*const\s+cellRegex\s*=\s*\/\[A-J\]\[1-9\]\[0-9\]\?\/(gi|ig)\s*;?\s*const\s+cellExpanded\s*=\s*rangeExpanded\.replace\(\s*cellRegex\s*,\s*(\(\s*match\s*\)|match)\s*=>\s*idToText\(\s*match\.toUpperCase\(\s*\)\s*\)\s*\)\s*;?\s*(?:const|let|var)\s+functionExpanded\s*=\s*applyFunction\(\s*cellExpanded\s*\)\s*;?\s*return\s+(?:functionExpanded\s*===\s*x|x\s*===\s*functionExpanded)\s*\?\s*functionExpanded\s*:\s*evalFormula\(/);

You should pass functionExpanded as the first argument to your evalFormula() call.

assert.match(code, /const\s+evalFormula\s*=\s*\(\s*x\s*,\s*cells\s*\)\s*=>\s*{\s*const\s+idToText\s*=\s*(\(\s*id\s*\)|id)\s*=>\s*cells\.find\(\s*(\(\s*cell\s*\)|cell)\s*=>\s*(?:cell\.id\s*===\s*id|id\s*===\s*cell\.id)\s*\)\.value\s*;?\s*const\s+rangeRegex\s*=\s*\/\(\[A-J\]\)\(\[1-9\]\[0-9\]\?\):\(\[A-J\]\)\(\[1-9\]\[0-9\]\?\)\/(gi|ig)\s*;?\s*const\s+rangeFromString\s*=\s*\(\s*num1\s*,\s*num2\s*\)\s*=>\s*range\(\s*parseInt\(\s*num1\s*\)\s*,\s*parseInt\(\s*num2\s*\)\s*\)\s*;?\s*const\s+elemValue\s*=\s*(\(\s*num\s*\)|num)\s*=>\s*(\(\s*character\s*\)|character)\s*=>\s*idToText\(\s*character\s*\+\s*num\s*\)\s*;?\s*const\s+addCharacters\s*=\s*(\(\s*character1\s*\)|character1)\s*=>\s*(\(\s*character2\s*\)|character2)\s*=>\s*(\(\s*num\s*\)|num)\s*=>\s*charRange\(\s*character1\s*,\s*character2\s*\)\.map\(\s*elemValue\(\s*num\s*\)\s*\)\s*;?\s*const\s+rangeExpanded\s*=\s*x\.replace\(\s*rangeRegex\s*,\s*\(\s*_match\s*,\s*char1\s*,\s*num1\s*,\s*char2\s*,\s*num2\s*\)\s*=>\s*rangeFromString\(\s*num1\s*,\s*num2\s*\)\.map\(\s*addCharacters\s*\(\s*char1\s*\)\(\s*char2\s*\)\s*\)\s*\)\s*;?\s*const\s+cellRegex\s*=\s*\/\[A-J\]\[1-9\]\[0-9\]\?\/(gi|ig)\s*;?\s*const\s+cellExpanded\s*=\s*rangeExpanded\.replace\(\s*cellRegex\s*,\s*(\(\s*match\s*\)|match)\s*=>\s*idToText\(\s*match\.toUpperCase\(\s*\)\s*\)\s*\)\s*;?\s*(?:const|let|var)\s+functionExpanded\s*=\s*applyFunction\(\s*cellExpanded\s*\)\s*;?\s*return\s+(?:functionExpanded\s*===\s*x|x\s*===\s*functionExpanded)\s*\?\s*functionExpanded\s*:\s*evalFormula\(\s*functionExpanded/);

You should pass cells as the second argument to your evalFormula() call.

assert.match(code, /const\s+evalFormula\s*=\s*\(\s*x\s*,\s*cells\s*\)\s*=>\s*{\s*const\s+idToText\s*=\s*(\(\s*id\s*\)|id)\s*=>\s*cells\.find\(\s*(\(\s*cell\s*\)|cell)\s*=>\s*(?:cell\.id\s*===\s*id|id\s*===\s*cell\.id)\s*\)\.value\s*;?\s*const\s+rangeRegex\s*=\s*\/\(\[A-J\]\)\(\[1-9\]\[0-9\]\?\):\(\[A-J\]\)\(\[1-9\]\[0-9\]\?\)\/(gi|ig)\s*;?\s*const\s+rangeFromString\s*=\s*\(\s*num1\s*,\s*num2\s*\)\s*=>\s*range\(\s*parseInt\(\s*num1\s*\)\s*,\s*parseInt\(\s*num2\s*\)\s*\)\s*;?\s*const\s+elemValue\s*=\s*(\(\s*num\s*\)|num)\s*=>\s*(\(\s*character\s*\)|character)\s*=>\s*idToText\(\s*character\s*\+\s*num\s*\)\s*;?\s*const\s+addCharacters\s*=\s*(\(\s*character1\s*\)|character1)\s*=>\s*(\(\s*character2\s*\)|character2)\s*=>\s*(\(\s*num\s*\)|num)\s*=>\s*charRange\(\s*character1\s*,\s*character2\s*\)\.map\(\s*elemValue\(\s*num\s*\)\s*\)\s*;?\s*const\s+rangeExpanded\s*=\s*x\.replace\(\s*rangeRegex\s*,\s*\(\s*_match\s*,\s*char1\s*,\s*num1\s*,\s*char2\s*,\s*num2\s*\)\s*=>\s*rangeFromString\(\s*num1\s*,\s*num2\s*\)\.map\(\s*addCharacters\s*\(\s*char1\s*\)\(\s*char2\s*\)\s*\)\s*\)\s*;?\s*const\s+cellRegex\s*=\s*\/\[A-J\]\[1-9\]\[0-9\]\?\/(gi|ig)\s*;?\s*const\s+cellExpanded\s*=\s*rangeExpanded\.replace\(\s*cellRegex\s*,\s*(\(\s*match\s*\)|match)\s*=>\s*idToText\(\s*match\.toUpperCase\(\s*\)\s*\)\s*\)\s*;?\s*(?:const|let|var)\s+functionExpanded\s*=\s*applyFunction\(\s*cellExpanded\s*\)\s*;?\s*return\s+(?:functionExpanded\s*===\s*x|x\s*===\s*functionExpanded)\s*\?\s*functionExpanded\s*:\s*evalFormula\(\s*functionExpanded\s*,\s*cells\s*\)\s*;?/);

--seed--

--seed-contents--

<!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" />
    <title>Functional Programming Spreadsheet</title>
  </head>
  <body>
    <div id="container">
      <div></div>
    </div>
    <script src="./script.js"></script>
  </body>
</html>

#container {
  display: grid;
  grid-template-columns: 50px repeat(10, 200px);
  grid-template-rows: repeat(11, 30px);
}

.label {
  background-color: lightgray;
  text-align: center;
  vertical-align: middle;
  line-height: 30px;
}

const infixToFunction = {
  "+": (x, y) => x + y,
  "-": (x, y) => x - y,
  "*": (x, y) => x * y,
  "/": (x, y) => x / y,
}

const infixEval = (str, regex) => str.replace(regex, (_match, arg1, operator, arg2) => infixToFunction[operator](parseFloat(arg1), parseFloat(arg2)));

const highPrecedence = str => {
  const regex = /([\d.]+)([*\/])([\d.]+)/;
  const str2 = infixEval(str, regex);
  return str === str2 ? str : highPrecedence(str2);
}

const isEven = num => num % 2 === 0;
const sum = nums => nums.reduce((acc, el) => acc + el, 0);
const average = nums => sum(nums) / nums.length;

const median = nums => {
  const sorted = nums.slice().sort((a, b) => a - b);
  const length = sorted.length;
  const middle = length / 2 - 1;
  return isEven(length)
    ? average([sorted[middle], sorted[middle + 1]])
    : sorted[Math.ceil(middle)];
}

const spreadsheetFunctions = {
  sum,
  average,
  median
}

const applyFunction = str => {
  const noHigh = highPrecedence(str);
  const infix = /([\d.]+)([+-])([\d.]+)/;
  const str2 = infixEval(noHigh, infix);
  const functionCall = /([a-z0-9]*)\(([0-9., ]*)\)(?!.*\()/i;
  const toNumberList = args => args.split(",").map(parseFloat);
  const apply = (fn, args) => spreadsheetFunctions[fn.toLowerCase()](toNumberList(args));
  return str2.replace(functionCall, (match, fn, args) => spreadsheetFunctions.hasOwnProperty(fn.toLowerCase()) ? apply(fn, args) : match);
}

const range = (start, end) => Array(end - start + 1).fill(start).map((element, index) => element + index);
const charRange = (start, end) => range(start.charCodeAt(0), end.charCodeAt(0)).map(code => String.fromCharCode(code));

--fcc-editable-region--
const evalFormula = (x, cells) => {
  const idToText = id => cells.find(cell => cell.id === id).value;
  const rangeRegex = /([A-J])([1-9][0-9]?):([A-J])([1-9][0-9]?)/gi;
  const rangeFromString = (num1, num2) => range(parseInt(num1), parseInt(num2));
  const elemValue = num => character => idToText(character + num);
  const addCharacters = character1 => character2 => num => charRange(character1, character2).map(elemValue(num));
  const rangeExpanded = x.replace(rangeRegex, (_match, char1, num1, char2, num2) => rangeFromString(num1, num2).map(addCharacters(char1)(char2)));
  const cellRegex = /[A-J][1-9][0-9]?/gi;
  const cellExpanded = rangeExpanded.replace(cellRegex, match => idToText(match.toUpperCase()));
  const functionExpanded = applyFunction(cellExpanded);

}
--fcc-editable-region--

window.onload = () => {
  const container = document.getElementById("container");
  const createLabel = (name) => {
    const label = document.createElement("div");
    label.className = "label";
    label.textContent = name;
    container.appendChild(label);
  }
  const letters = charRange("A", "J");
  letters.forEach(createLabel);
  range(1, 99).forEach(number => {
    createLabel(number);
    letters.forEach(letter => {
      const input = document.createElement("input");
      input.type = "text";
      input.id = letter + number;
      input.ariaLabel = letter + number;
      input.onchange = update;
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    })
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}

const update = event => {
  const element = event.target;
  const value = element.value.replace(/\s/g, "");
  if (!value.includes(element.id) && value.startsWith('=')) {

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}