freeCodeCamp/part-017.md at 104a8068e323ac304f68eac64873bce1dc79b4b3

Randell Dawson b9c9a95223 chore(learn): Renamed all project-based curriculum project step filenames to use 3-digit format of part-ddd.md (#39463 )

* fix: renamed basic html cat photo app steps

* fix: renamed css-variables project steps

* fix: renamed d3-dashboard filenames

* fix: renamed rpg-game filenames

* fix: renamed functional-progamming-spreadsheet filenames

* fix: renamed calorie-counter project filenames

2020-09-16 11:54:12 +05:30

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id, title, challengeType, isHidden

id	title	challengeType	isHidden
5d79253386060ed9eb04a070	Part 17	0	true

Description

The match parameter is currently unused, which can lead to unused variable warnings in some linters.

To fix this, prefix or replace it with an underscore (_) - both ways signal to the reader and linter that you're aware you don't need this.

Note that a single underscore can only be used once in a function and may conflict with some libraries (Lodash, Underscore.js).

Instructions

Tests

tests:
  - text: See description above for instructions.
    testString: assert(code.replace(/\s/g, "").includes("str.replace(regex,(_"));

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


</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))
  );
</script>

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