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JavaScript Express Basics Parameters, Query Strings, and Modularizing Routes Linking Around the Application

Casey Dixon
Casey Dixon
8,920 Points
Posted by Casey Dixon
Casey Dixon
8,920 Points

Scope and template data

Are you able to pass a variable from outside the scope of a router function, such as a global variable, into a route's template data? Or must the variable come from within the scope of the route function?

router.get('/:id', (req, res) => {
    const { side } = req.query;
    const { id } = req.params;
    const text = cards[id][side];
    const { hint } = cards[id];
    const numberOfCards = cards.length;
    const randomId = Math.floor(Math.random() * numberOfCards);

    const templateData = { text, id, randomId };

This works, where the randomId is declared in the scope of the function, but when it is declared outside of the function it does not work:

const numberOfCards = cards.length;
const randomId = Math.floor(Math.random() * numberOfCards);

router.get('/:id', (req, res) => {
    const { side } = req.query;
    const { id } = req.params;
    const text = cards[id][side];
    const { hint } = cards[id];

    const templateData = { text, id, randomId };

I know functions have access to variables outside their scope, but I'm wondering if there is an issue with passing that global variable into a route's template data.