How to use or in ternary operator in javascript?

I want to write a ternary operator in js that do the following:

If index equals 1 or 3, set var x to 10, else set var x to 0.

How do i continue here?

Currently i have this:

let x = 0
const arr = ['string', 'string', 'string', 'string', 'string', 'string etc']

arr.forEach((el, index) => {
  index ? == 1 || index ? == 3
})

>Solution :

You can set the value of x within the forEach loop based on the condition .I’ve added a code snippet.

const arr = ['string', 'string', 'string', 'string', 'string', 'string', 'etc']

arr.forEach((el, index) => {
  const x = (index === 1 || index === 3) ? 10 : 0
  console.log(`index is ${index} and x is ${x}`)
});