function checkStore(string) {
    for (var i = 0; i < BookStore.length; i++) {
        if (BookStore[i].title === string) {
            prompt('We found your book! ' + string + ', by ' + BookStore[i].author +
                '. It costs ' + BookStore[i].price +
                ' would you like to add it to your cart?');
        } else {
            alert('Sorry ' + string + ' was not found, try another title?');
        }
    }
}

This is what happens lets say the BookStore.length = 6. If BookStore[i].title === string is true at index 4 this is what i get

'Sorry ' + string + ' was not found, try another title?'
'Sorry ' + string + ' was not found, try another title?'
'Sorry ' + string + ' was not found, try another title?'
'Sorry ' + string + ' was not found, try another title?'
'We found your book! ' + string + ', by ' + BookStore[i].author +
                    '. It costs ' + BookStore[i].price +
                    ' would you like to add it to your cart?'
'Sorry ' + string + ' was not found, try another title?'

How do i get it to just print 'Sorry ' + string + ' was not found, try another title?' once when not true and

'We found your book! ' + string + ', by ' + BookStore[i].author +
                        '. It costs ' + BookStore[i].price +
                        ' would you like to add it to your cart?'

by itself when true?

Thank you!

A solution with Array.prototype.some():

function checkStore(string) {
    var book;
    if (BookStore.some(function (b) {
        return b.title === string && (book = b);
    })) {
        prompt('We found your book! ' + string + ', by ' + book.author + '. It costs ' + book.price + ' would you like to add it to your cart?');
    } else {
        alert('Sorry ' + string + ' was not found, try another title?');
    }
}

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