Node / Express / Nunjucks: TypeError: Cannot use 'in' operator to search for 'x' in 'y'

Question

Im new to the world of Nunjucks / Express and Node.

I have a routes file which is porting in the value of an input from a form field. I need to check if the value contains the expression 'gov'.

So i created the following:

router.get('/test/output/', function (req, res) {
  var emailAdress = req.session.data['accountEmail']
  if ('gov' in emailAdress){
    isCS = true
  }
  res.render('test/output.html',{
    'email' : emailAdress,

.... and so on...

And this gives me the following error:

TypeError: Cannot use 'in' operator to search for 'gov' in '[email protected]'

I understand that this is to do with objects and arrays - I just cannot find the solution - I appreciate its probably straightforward. Any help is much appreciated.

Answer 1

The in operator only works on objects, not string primitives.

To search within a string, you can use includes:

emailAdress.includes('gov')

An ES5 compatible version (before includes existed):

emailAdress.indexOf('gov') !== -1

Or perhaps you can check if the string ends with 'gov':

emailAdress.endsWith('gov')