replace and split
- Node.js course
- Beginner
- Lesson 33/116
- 5 min
Learn to modify strings with .replace and .split.
Replacing with replace
To replace a substring with another you use .replace(search, replacement). "cold-cold".replace("cold", "warm") changes only the first match and returns "warm-cold".
To replace every match you have two options: a regular expression like /cold/g or the .replaceAll() method. "cold-cold".replaceAll("cold", "warm") returns "warm-warm". replace and replaceAll do not modify the original; they return a new string.
Splitting into an array
To break a string into parts you use .split(separator). The string is split wherever the separator appears and the parts are placed in an array. "apple,pear,banana".split(",") returns ["apple", "pear", "banana"].
If the separator is an empty string each character becomes a separate element: "abc".split("") gives ["a", "b", "c"]. split is especially useful for comma-separated values (CSV); you split each line into pieces and reach the fields.
Practice Split the list into an array
The csv variable holds "Notebook,Pen,Eraser". Declare a variable items and assign the result of csv.split(",") to it. Then print items[0] with console.log. The output on a single line must be Notebook.
Starter code
const csv = "Notebook,Pen,Eraser";
// Declare items with split; print the first elementSample solution
const csv = "Notebook,Pen,Eraser";
const items = csv.split(",");
console.log(items[0]);Expected output
Notebook
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What is the result of "a-b".replace("-", "/")?
"a-b".replace("-", "/")- "a-b"
- "a/b" Correct answer
- "a/b/c"
- "/"
Explanation: replace changes the first '-' to '/'; the result is "a/b".
2 Match each method to its job
| Term | Meaning |
|---|---|
.replace(x, y) |
Changes first match |
.replaceAll(x, y) |
Changes every match |
.split(x) |
Splits into array |
.slice(a, b) |
Takes a part |
3 Write the split call
const line = "a,b,c";
const parts = line____(",");const line = "a,b,c";
const parts = line.split(",");Explanation: .split breaks the string by separator into an array.