freeCodeCamp

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id	title	challengeType
5d79253770083fb730c93a93	Part 95	0

Description

You don't have to specify the second argument in slice. If you don't, then slice will extract from the first argument to the end of the string.

Change the call to slice to log all characters except the first instead.

Instructions

Tests

tests:
  - text: See description above for instructions.
    testString: assert(code.replace(/\s/g, "").includes("console.log(value.slice(1))"));

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 spreadsheetFunctions = {
  "": x => x
};

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 => {
  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 => document.getElementById(c + n).value;
  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 => document.getElementById(match.toUpperCase()).value
  );
  const functionExpanded = applyFn(varExpanded);
  return functionExpanded === x
    ? functionExpanded
    : evalFormula(functionExpanded);
};

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] === "=") {
    console.log(value.slice(0, 2));
  }
};


</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 spreadsheetFunctions = {
  "": x => x
};

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 => {
  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 => document.getElementById(c + n).value;
  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 => document.getElementById(match.toUpperCase()).value
  );
  const functionExpanded = applyFn(varExpanded);
  return functionExpanded === x
    ? functionExpanded
    : evalFormula(functionExpanded);
};

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] === "=") {
    console.log(value.slice(1));
  }
};
</script>

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