freeCodeCamp/part-031.md at 895e6b8daf6338920221fa33ff4be59eef815e89

chore(learn): Remove remaining isHidden keys from frontmatter (English and Chinese challenges) (#39809 )

* fix: remove isHidden key from tool template

* fix: removed isHidden key from English challenges

* fix: remove isHidden key from Chinese challenges

2020-10-08 14:18:47 +02:00

3.0 KiB

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id, title, challengeType

id	title	challengeType
5d792534c3d26890ac1484d4	Part 31	0

Description

The map method takes a function and for each element of an array, it passes the element to the function and replace the element with the return value:

[1, 2, 3].map(x => x + 1); // [2, 3, 4]

In toNumberList, chain the map method to args.split(",") and pass it parseFloat to parse each element of the array into a number.

Instructions

Tests

tests:
  - text: See description above for instructions.
    testString: assert(code.replace(/\s/g, "").includes('consttoNumberList=args=>args.split(",").map(parseFloat)'));

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(",");
}


</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);
}
</script>

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