freeCodeCamp/curriculum/challenges/italian/15-javascript-algorithms-an.../learn-functional-programmin.../step-014.md

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---
id: 5d792533a5c42fb4d1a4b70d
title: Step 14
challengeType: 0
dashedName: step-14
---
# --description--
Replace the second argument of `str.replace` with an anonymous function, which takes `match`, `arg1`, `fn`, and `arg2`, and returns `infixToFunction["+"]`.
# --hints--
See description above for instructions.
```js
assert(
code
.replace(/\s/g, '')
.includes('str.replace(regex,(match,arg1,fn,arg2)=>infixToFunction["+"])')
);
```
# --seed--
## --before-user-code--
```html
<!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-user-code--
```html
</body>
</html>
```
## --seed-contents--
```html
<script>
const infixToFunction = {
"+": (x, y) => x + y,
"-": (x, y) => x - y,
"*": (x, y) => x * y,
"/": (x, y) => x / y
};
--fcc-editable-region--
const infixEval = (str, regex) => str.replace(regex, infixToFunction["+"]);
--fcc-editable-region--
</script>
```
# --solutions--
```html
<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["+"]
);
</script>
```