Search function for a value in an array of objects

Question

I have tried to create a function which searches for the title in an array of book-objects. For some reason my code doesn't work, I have tried going through each step logically and in my mind it should be working.

let book = {
 title: "The 48 Laws of Power",
 author: "Robert Greene",
 numOfPages: 452,
 publisher: "Penguin Books",
 rating: "4.5 stars"
}
let book2 = {
 title: "How to Catch a Turkey",
 author: "Adam Wallace",
 numOfPages: 40,
 publisher: "",
 rating: "5 stars"
}
let book3 = {
 title: "Glitter Every Day: 365 Quotes from Women I Love",
 author: "Andy Cohen",
 numOfPages: 384,
 publisher: "Henry Holt and Co.",
 rating: "3 stars"
}
let bookArr = [book, book2, book3];
let searchBtn = document.getElementById('search-button');
let found = false;
let bookSearch = function() {
 found = false;
 let input = document.getElementById('book-search');
 for (i = 0; i < bookArr.length; i++) {
 if (input.value.toLowerCase == bookArr[i].title.toLowerCase) {
 found = true;
 break;
 }
 }
 if (found) {
 console.log(bookArr[i]);
 } else {
 console.log("The book was not found.");
 }
}
searchBtn.addEventListener('click', bookSearch);

<input type="text" id="book-search" placeholder="Search books...">
<button id="search-button">Search</button>
<script src="object.js"></script>

And lastly I'm new to this forum and also new to programming so I apologize if this is the wrong way of asking questions but I would really appreciate some criticism on my code and what I should do better. Thank you!

• h0r53: Have you tried using your browser's dev tools to debug the bookSearch function?
• Dario: toLowerCase is a function, you should invoke it using (): toLowerCase()

Answer 1

You can use Array.find() and it's as easy as:

var book = bookArr.find(book => book.title.toLowerCase() == input.value.toLowerCase())

Working Demo

let book = {
 title: "The 48 Laws of Power",
 author: "Robert Greene",
 numOfPages: 452,
 publisher: "Penguin Books",
 rating: "4.5 stars"
}
let book2 = {
 title: "How to Catch a Turkey",
 author: "Adam Wallace",
 numOfPages: 40,
 publisher: "",
 rating: "5 stars"
}
let book3 = {
 title: "Glitter Every Day: 365 Quotes from Women I Love",
 author: "Andy Cohen",
 numOfPages: 384,
 publisher: "Henry Holt and Co.",
 rating: "3 stars"
}
let bookArr = [book, book2, book3];
let searchBtn = document.getElementById('search-button');
let found = false;
let bookSearch = function() {
 let input = document.getElementById('book-search');
 var book = bookArr.find(book => book.title.toLowerCase() == input.value.toLowerCase())
 if (book) {
 console.log(book);
 } else {
 console.log("The book was not found.");
 }
}
searchBtn.addEventListener('click', bookSearch);

<input type="text" id="book-search" placeholder="Search books...">
<button id="search-button">Search</button>
<script src="object.js"></script>

Answer 2

If you want only the first match, use Array.find().

books.find(book => book.title == 'mysearch');

If you want an array of matches use Array.filter().

books.filter(book => book.title == 'mysearch');

If you are using Typescript, then you can add type safety and make the search function easier to use.

function search<Type, Key extends keyof Type>(arr: Type[], prop: Key, match: Type[Key]){
 // For a single item
 return arr.find(item => item[prop] == match);
 // For an array of matches
 return arr.filter(item => item[prop] == match);
}

Then we make an interface for a book and we can easily search it while having auto-complete.

interface Book {
 title: string;
 author: string;
 numOfPages: number;
 publisher: string
 rating: string;
}
search(books, "title", "Harry Potter")

Here's a TS playground to try the code yourself. Link

• Invizi: @Icepickle Thanks. It's hard to see mistakes when writing on a phone.