Having trouble navigating through filtering in JavaScript using Node and Express?

Question

Having trouble navigating through filtering in JavaScript using Node and Express?

After experimenting with different methods, I noticed that when using

(age => age.Book === book && age.Chapter === 1)

as my filter criteria, everything works perfectly.

However, when I try using

(age => age.Book === book && age.Chapter === chapter)

, the filter does not work as expected.

I found that if I use a hardcoded number or string for 'chapter', rather than a variable, it works just fine. But once I introduce a variable for 'chapter', things stop working.

All of my chapters are represented by numbers. Interestingly, changing one chapter to a string (a word instead of a number) caused my 'chapter' variable to start working.

Can anyone shed some light on how I can make my 'chapter' variable function properly?

app.get("/book/:bookTitle/:bookChapter/", function(req, res){
    const book = req.params.bookTitle;
    const chapter = req.params.bookChapter;
    const verse = req.params.bookVerse;
    const text = req.params.bookText;

    const getBook = verseList.filter(age => age.Book === book && age.Chapter === 1);

    const getBook = verseList.filter(age => age.Book === book && age.Chapter === chapter);

javascript express filter

Answer 1

Answer №1

You're almost there! The variable req.params.bookChapter is stored as a string, while the array items are numbers. To fix this, simply convert req.params.bookChapter into a number.

const chapter = Number(req.params.bookChapter);

Answer 2

You're almost there! The variable req.params.bookChapter is stored as a string, while the array items are numbers. To fix this, simply convert req.params.bookChapter into a number.

const chapter = Number(req.params.bookChapter);

Answer 3

Answer №2

In case you missed it, remember that you cannot declare the same name twice.

Also, your code will only work if they are both of the same type!

For instance:

const animals = [];
for (let j=0; j < 100; j++) {
    animals[j] = ({
        Type: "mammal"+Math.round(j/10),
        Species: (j%10) + 1
    });
}
console.log(animals);
const type = "mammal7";
// const species = "7";//This won't work for the second filter!
const species = 7;

const getMammal = animals.filter(animal => animal.Type === type && animal.Species === 1);
console.log(getMammal);
const getMammal2 = animals.filter(animal => animal.Type === type && animal.Species === species);
console.log(getMammal2);

Answer 4

In case you missed it, remember that you cannot declare the same name twice.

Also, your code will only work if they are both of the same type!

For instance:

const animals = [];
for (let j=0; j < 100; j++) {
    animals[j] = ({
        Type: "mammal"+Math.round(j/10),
        Species: (j%10) + 1
    });
}
console.log(animals);
const type = "mammal7";
// const species = "7";//This won't work for the second filter!
const species = 7;

const getMammal = animals.filter(animal => animal.Type === type && animal.Species === 1);
console.log(getMammal);
const getMammal2 = animals.filter(animal => animal.Type === type && animal.Species === species);
console.log(getMammal2);

Having trouble navigating through filtering in JavaScript using Node and Express?

Answer №1

Answer №2

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