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

Lewis Marshall
Lewis Marshall
22,673 Points
Posted by Lewis Marshall
Lewis Marshall
22,673 Points

My solution to handle invalid query string key 'side' value

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

  // checks the side value is included in the array 
  const invalidQueryString = !["question", "answer"].includes(side); 

  if (!side || invalidQueryString) {
    res.redirect(`/cards/${id}?side=question`);
  } else {
    const name = req.cookies.username;
    const text = cards[id][side];
    const { hint } = cards[id];

    const templateData = { text, id, side, name };

    if (side === "question") {
      templateData.hint = hint;
    } 

    res.render('card', templateData);
  }
});

1 Answer

Trevor Maltbie
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.a{fill-rule:evenodd;}techdegree seal-36
Trevor Maltbie
Full Stack JavaScript Techdegree Graduate 17,021 Points
Trevor Maltbie
.a{fill-rule:evenodd;}techdegree seal-36
Trevor Maltbie
Full Stack JavaScript Techdegree Graduate 17,021 Points

Good thinking, Lewis. Using the includes method is a good approach.

I had thought of something similar:

  if ( side !== 'answer' || side !== 'question' ) {
    res.redirect(`/cards/${id}?side=question`)
  }

However, this leads to an infinite amount of redirects and crashes the site.

EDIT: I just realized that this is failing because if || operator. If it's not answer but it is question it just keeps bouncing back and forth.

The solution is to make use && operator.