Create function in javascript

Question

I have a function that in thesis is to make a check if the variable x is equal to the variable y.

function teste(x){
   if (x == 'y*') {
     alert('igual')
   } else {
     alert('diferente')
   }

}

I want you to check if it’s y and start with y. That’s why I put the *, to take everything that comes after, but it doesn’t work.

Answer 1

The comparison x == 'y*' will only be true when x be exactly the string 'y*', that is, two characters being a letter Y and an asterisk.

If the idea is to check whether x starts with the letter Y, just use the function String.prototype.startsWith:

if (x.startsWith('y')) {
    ...
}

Answer 2

Another option would be to use the method charAt()

The charAt() method returns the specified character from a string. If the index you provide is outside the index range of the string, Javascript will return an empty string. If no index is passed to . charAt(), 0 (zero) will be used by default

if (x.charAt() === 'y'){
   //...
}

Answer 3

The indexOf returns the position of a string in another string or -1 if you don’t find.

var s = "foo";
alert(s.indexOf("oo") != -1);