freeCodeCamp/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/functional-programming-spreadsheet/part-136.md

id, title, challengeType

id	title	challengeType
5d79253a2febbb77098730b9	Part 136	0

Description

The every method checks if all elements of an array satisfy the provided testing function.

Use it to add an everyeven function to spreadsheetFunctions which checks if all values passed in are evenspreadsheetFunctions which checks if all values passed in are even.

Instructions

Tests

tests:
  - text: See description above for instructions.
    testString: assert(spreadsheetFunctions.everyeven([2, 6, 4, 0, 20]) && !spreadsheetFunctions.everyeven([10, 0, 9, 2]) && code.includes(".every"));

Challenge Seed

<script>

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, (_, arg1, fn, arg2) =>
    infixToFunction[fn](parseFloat(arg1), parseFloat(arg2))
  );

const highPrecedence = str => {
  const regex = /([0-9.]+)([*\/])([0-9.]+)/;
  const str2 = infixEval(str, regex);
  return str === str2 ? str : highPrecedence(str2);
};

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

const median = nums => {
  const sorted = nums.slice().sort((x, y) => x - y);
  const length = sorted.length;
  const middle = sorted.length / 2 - 1;
  return isEven(length)
    ? average([sorted[middle], sorted[middle + 1]])
    : sorted[middle + 0.5];
}; 

const spreadsheetFunctions = {
  "": x => x,
  random: ([x, y]) => Math.floor(Math.random() * y + x),
  increment: nums => nums.map(x => x + 1),
  firsttwo: arr => arr.slice(0, 2),
  lasttwo: arr => arr.slice(-2),
  even: nums => nums.filter(isEven),
  sum,
  average,
  median,
  has2: arr => arr.includes(2),
  nodups: arr => arr.reduce((a, x) => a.includes(x) ? a : a.concat(x), []),
  range: arr => range(...arr),
  someeven: arr => arr.some(isEven)
};



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

const range = (start, end) =>
  start > end ? [] : [start].concat(range(start + 1, end));

const charRange = (start, end) =>
  range(start.charCodeAt(0), end.charCodeAt(0)).map(x =>
    String.fromCharCode(x)
  );

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 = (n1, n2) => range(parseInt(n1), parseInt(n2));
  const elemValue = n => c => idToText(c + n);
  const addChars = c1 => c2 => n => charRange(c1, c2).map(elemValue(n));
  const varRangeExpanded = x.replace(rangeRegex, (_, c1, n1, c2, n2) =>
    rangeFromString(n1, n2).map(addChars(c1)(c2))
  );
  const varRegex = /[A-J][1-9][0-9]?/gi;
  const varExpanded = varRangeExpanded.replace(
    varRegex,
    match => idToText(match.toUpperCase())
  );
  const functionExpanded = applyFn(varExpanded);
  return functionExpanded === x
    ? functionExpanded
    : evalFormula(functionExpanded, cells);
};

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(x => {
    createLabel(x);
    letters.forEach(y => {
      const input = document.createElement("input");
      input.type = "text";
      input.id = y + x;
      input.onchange = update;
      container.appendChild(input);
    });
  });
};

const update = event => {
  const element = event.target;
  const value = element.value.replace(/\s/g, "");
  if (!value.includes(element.id) && value[0] === "=") {
    element.value = evalFormula(
      value.slice(1),
      Array.from(document.getElementById("container").children)
    );
  }
};
</script>

Before Test

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Spreadsheet</title>
  <style>
    #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;
    }
  </style>
</head>
<body>
<div id="container">
  <div></div>
</div>

After Test

</body>
</html>

Solution

<script>
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, (_, arg1, fn, arg2) =>
    infixToFunction[fn](parseFloat(arg1), parseFloat(arg2))
  );

const highPrecedence = str => {
  const regex = /([0-9.]+)([*\/])([0-9.]+)/;
  const str2 = infixEval(str, regex);
  return str === str2 ? str : highPrecedence(str2);
};

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

const median = nums => {
  const sorted = nums.slice().sort((x, y) => x - y);
  const length = sorted.length;
  const middle = sorted.length / 2 - 1;
  return isEven(length)
    ? average([sorted[middle], sorted[middle + 1]])
    : sorted[middle + 0.5];
}; 

const spreadsheetFunctions = {
  "": x => x,
  random: ([x, y]) => Math.floor(Math.random() * y + x),
  increment: nums => nums.map(x => x + 1),
  firsttwo: arr => arr.slice(0, 2),
  lasttwo: arr => arr.slice(-2),
  even: nums => nums.filter(isEven),
  sum,
  average,
  median,
  has2: arr => arr.includes(2),
  nodups: arr => arr.reduce((a, x) => a.includes(x) ? a : a.concat(x), []),
  range: arr => range(...arr),
  someeven: arr => arr.some(isEven),
  everyeven: arr => arr.every(isEven)
};

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

const range = (start, end) =>
  start > end ? [] : [start].concat(range(start + 1, end));



const charRange = (start, end) =>
  range(start.charCodeAt(0), end.charCodeAt(0)).map(x =>
    String.fromCharCode(x)
  );

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 = (n1, n2) => range(parseInt(n1), parseInt(n2));
  const elemValue = n => c => idToText(c + n);
  const addChars = c1 => c2 => n => charRange(c1, c2).map(elemValue(n));
  const varRangeExpanded = x.replace(rangeRegex, (_, c1, n1, c2, n2) =>
    rangeFromString(n1, n2).map(addChars(c1)(c2))
  );
  const varRegex = /[A-J][1-9][0-9]?/gi;
  const varExpanded = varRangeExpanded.replace(
    varRegex,
    match => idToText(match.toUpperCase())
  );
  const functionExpanded = applyFn(varExpanded);
  return functionExpanded === x
    ? functionExpanded
    : evalFormula(functionExpanded, cells);
};

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(x => {
    createLabel(x);
    letters.forEach(y => {
      const input = document.createElement("input");
      input.type = "text";
      input.id = y + x;
      input.onchange = update;
      container.appendChild(input);
    });
  });
};

const update = event => {
  const element = event.target;
  const value = element.value.replace(/\s/g, "");
  if (!value.includes(element.id) && value[0] === "=") {
    element.value = evalFormula(
      value.slice(1),
      Array.from(document.getElementById("container").children)
    );
  }
};
</script>