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171 lines
6.1 KiB
Markdown
171 lines
6.1 KiB
Markdown
---
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id: 646d40fe4b7b50c30c2b4cd8
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title: Step 78
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challengeType: 0
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dashedName: step-78
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---
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# --description--
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Your `infixEval` function will only evaluate the first multiplication or division operation, because `regex` isn't global. This means you'll want to use a recursive approach to evaluate the entire string.
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If `infixEval` does not find any matches, it will return the `str` value as-is. Using a ternary expression, check if `str2` is equal to `str`. If it is, return `str`, otherwise return the result of calling `highPrecedence()` on `str2`.
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# --hints--
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Your `highPrecedence` function should use the `return` keyword.
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```js
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assert.match(code, /const\s+highPrecedence\s*=\s*(\(\s*str\s*\)|str)\s*=>\s*{\s*const\s+regex\s*=\s*\/\(\[(?:\\d\.|\.\\d)\]\+\)\(\[(?:\*\\\/|\\\/*)\]\)\(\[(?:\\d\.|\.\\d)\]\+\)\/\s*;?\s*const\s+str2\s*=\s*infixEval\(\s*str\s*,\s*regex\s*\)\s*;?\s*return/);
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```
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You should use the `return` keyword with a condition to check if `str` is equal to `str2`.
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```js
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assert.match(code, /const\s+highPrecedence\s*=\s*(\(\s*str\s*\)|str)\s*=>\s*{\s*const\s+regex\s*=\s*\/\(\[(?:\\d\.|\.\\d)\]\+\)\(\[(?:\*\\\/|\\\/*)\]\)\(\[(?:\\d\.|\.\\d)\]\+\)\/\s*;?\s*const\s+str2\s*=\s*infixEval\(\s*str\s*,\s*regex\s*\)\s*;?\s*return\s+(?:str\s*===\s*str2|str2\s*===\s*str)/);
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```
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You should use ternary syntax with your `return` statement.
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```js
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assert.match(code, /const\s+highPrecedence\s*=\s*(\(\s*str\s*\)|str)\s*=>\s*{\s*const\s+regex\s*=\s*\/\(\[(?:\\d\.|\.\\d)\]\+\)\(\[(?:\*\\\/|\\\/*)\]\)\(\[(?:\\d\.|\.\\d)\]\+\)\/\s*;?\s*const\s+str2\s*=\s*infixEval\(\s*str\s*,\s*regex\s*\)\s*;?\s*return\s+(?:str\s*===\s*str2|str2\s*===\s*str)\s*\?/);
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```
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If the ternary condition is true, you should return `str`.
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```js
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assert.match(code, /const\s+highPrecedence\s*=\s*(\(\s*str\s*\)|str)\s*=>\s*{\s*const\s+regex\s*=\s*\/\(\[(?:\\d\.|\.\\d)\]\+\)\(\[(?:\*\\\/|\\\/*)\]\)\(\[(?:\\d\.|\.\\d)\]\+\)\/\s*;?\s*const\s+str2\s*=\s*infixEval\(\s*str\s*,\s*regex\s*\)\s*;?\s*return\s+(?:str\s*===\s*str2|str2\s*===\s*str)\s*\?\s*str/);
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```
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If the ternary condition is false, you should return the result of calling `highPrecedence()`.
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```js
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assert.match(code, /const\s+highPrecedence\s*=\s*(\(\s*str\s*\)|str)\s*=>\s*{\s*const\s+regex\s*=\s*\/\(\[(?:\\d\.|\.\\d)\]\+\)\(\[(?:\*\\\/|\\\/*)\]\)\(\[(?:\\d\.|\.\\d)\]\+\)\/\s*;?\s*const\s+str2\s*=\s*infixEval\(\s*str\s*,\s*regex\s*\)\s*;?\s*return\s+(?:str\s*===\s*str2|str2\s*===\s*str)\s*\?\s*str\s*:\s*highPrecedence\(/);
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```
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You should pass `str2` to your `highPrecedence()` call.
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```js
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assert.match(code, /const\s+highPrecedence\s*=\s*(\(\s*str\s*\)|str)\s*=>\s*{\s*const\s+regex\s*=\s*\/\(\[(?:\\d\.|\.\\d)\]\+\)\(\[(?:\*\\\/|\\\/*)\]\)\(\[(?:\\d\.|\.\\d)\]\+\)\/\s*;?\s*const\s+str2\s*=\s*infixEval\(\s*str\s*,\s*regex\s*\)\s*;?\s*return\s+(?:str\s*===\s*str2|str2\s*===\s*str)\s*\?\s*str\s*:\s*highPrecedence\(\s*str2\s*\)/);
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```
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# --seed--
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## --seed-contents--
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```html
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<!DOCTYPE html>
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<html lang="en">
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<head>
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<meta charset="utf-8" />
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<meta name="viewport" content="width=device-width, initial-scale=1" />
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<link rel="stylesheet" href="./styles.css" />
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<title>Functional Programming Spreadsheet</title>
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</head>
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<body>
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<div id="container">
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<div></div>
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</div>
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<script src="./script.js"></script>
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</body>
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</html>
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```
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```css
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#container {
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display: grid;
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grid-template-columns: 50px repeat(10, 200px);
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grid-template-rows: repeat(11, 30px);
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}
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.label {
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background-color: lightgray;
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text-align: center;
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vertical-align: middle;
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line-height: 30px;
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}
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```
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```js
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const infixToFunction = {
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"+": (x, y) => x + y,
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"-": (x, y) => x - y,
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"*": (x, y) => x * y,
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"/": (x, y) => x / y,
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}
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const infixEval = (str, regex) => str.replace(regex, (_match, arg1, operator, arg2) => infixToFunction[operator](parseFloat(arg1), parseFloat(arg2)));
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--fcc-editable-region--
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const highPrecedence = str => {
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const regex = /([\d.]+)([*\/])([\d.]+)/;
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const str2 = infixEval(str, regex);
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}
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--fcc-editable-region--
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const isEven = num => num % 2 === 0;
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const sum = nums => nums.reduce((acc, el) => acc + el, 0);
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const average = nums => sum(nums) / nums.length;
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const median = nums => {
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const sorted = nums.slice().sort((a, b) => a - b);
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const length = sorted.length;
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const middle = length / 2 - 1;
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return isEven(length)
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? average([sorted[middle], sorted[middle + 1]])
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: sorted[Math.ceil(middle)];
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}
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const spreadsheetFunctions = {
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sum,
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average,
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median
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}
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const range = (start, end) => Array(end - start + 1).fill(start).map((element, index) => element + index);
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const charRange = (start, end) => range(start.charCodeAt(0), end.charCodeAt(0)).map(code => String.fromCharCode(code));
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const evalFormula = (x, cells) => {
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const idToText = id => cells.find(cell => cell.id === id).value;
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const rangeRegex = /([A-J])([1-9][0-9]?):([A-J])([1-9][0-9]?)/gi;
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const rangeFromString = (num1, num2) => range(parseInt(num1), parseInt(num2));
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const elemValue = num => character => idToText(character + num);
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const addCharacters = character1 => character2 => num => charRange(character1, character2).map(elemValue(num));
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const rangeExpanded = x.replace(rangeRegex, (_match, char1, num1, char2, num2) => rangeFromString(num1, num2).map(addCharacters(char1)(char2)));
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const cellRegex = /[A-J][1-9][0-9]?/gi;
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const cellExpanded = rangeExpanded.replace(cellRegex, match => idToText(match.toUpperCase()));
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}
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window.onload = () => {
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const container = document.getElementById("container");
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const createLabel = (name) => {
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const label = document.createElement("div");
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label.className = "label";
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label.textContent = name;
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container.appendChild(label);
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}
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const letters = charRange("A", "J");
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letters.forEach(createLabel);
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range(1, 99).forEach(number => {
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createLabel(number);
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letters.forEach(letter => {
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const input = document.createElement("input");
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input.type = "text";
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input.id = letter + number;
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input.ariaLabel = letter + number;
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input.onchange = update;
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container.appendChild(input);
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})
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})
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}
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const update = event => {
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const element = event.target;
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const value = element.value.replace(/\s/g, "");
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if (!value.includes(element.id) && value.startsWith('=')) {
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}
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}
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```
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