Summary - Advanced string methods
- JavaScript course
- Beginner
- Lesson 110/133
- 5 min
Build a function that reverses a sentence word by word using split, map and join.
Summary - Advanced string methods
In this group you met the advanced string methods. With slice and substring you took parts; with replace and replaceAll you swapped values; with split and join you moved between strings and arrays.
trim, padStart and padEnd cleaned whitespace and padded to a target width. Finally toUpperCase, toLowerCase and includes handled case work.
Practice Reverse a sentence word by word
Split the sentence string into words, reverse their order with map and join them back with a space. Store the result in reversed and print it. Hint: inside map you can use arr[arr.length - 1 - i].
Starter code
const sentence = "javascript is a great language";
// split words, reverse their order, join
const reversed = sentence;
console.log(reversed);Sample solution
const sentence = "javascript is a great language";
// split words, reverse their order, join
const reversed = sentence.split(" ").map((word, i, arr) => arr[arr.length - 1 - i]).join(" ");
console.log(reversed);Practice Build a slug from a title
Build a slug from title: first trim the spaces, then lowercase with toLowerCase, then replace every space with a dash. Store the result in slug and print it.
Starter code
const title = " JavaScript Lessons ";
// trim, lowercase, replace spaces with dashes
const slug = title;
console.log(slug);Sample solution
const title = " JavaScript Lessons ";
// trim, lowercase, replace spaces with dashes
const slug = title.trim().toLowerCase().replaceAll(" ", "-");
console.log(slug);Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Match method to use
| Term | Meaning |
|---|---|
slice(-3) |
last three chars |
replaceAll("a","b") |
change all a |
split(",") |
split on comma |
trim() |
strip edge spaces |
2 Split the sentence into words and join with a dash
const sentence = "javascript is a great language";
const slug = sentence.____("-").trim();
console.log(slug);const sentence = "javascript is a great language";
const slug = sentence.split(" ").join("-").trim();
console.log(slug);Explanation: split(" ").join("-") glues the words with a dash.