public/subjects/half-a-million

Half a million

Using variables as keys

One possible and very useful way to get something from an object is using a variable value. Sometimes you don't know in advance what the key will be.

Using variables allows your code to be flexible, let's see how to do it

let greeting = 'hello'
let say = { hello: 'my friend', hoy: 'mate' }

// Here when we access it will use
console.log(say[greeting]) // -> 'my friend'

// It is exactly the same as doing
console.log(say['hello']) // -> 'my friend'

// But if we change the value of our variable:
greeting = 'hoy'

// The same code now returns another value
console.log(say[greeting]) // -> 'mate'

We are using the value of the variable, not the identifier to access the property, so:

console.log(say[greeting]) // -> 'mate'
console.log(say['greeting']) // -> undefined
console.log(say.greeting) // -> undefined
// greeting is the identifier, but we use it's value, here `'hoy'`

Instructions

In this exercise, we will do a heist.

Our intel already worked the plan out and we are able to provide you with 2 variables:

• a vault object
• a secret string

You must use the secret value as a key to access the matching value from the vault and assign it to a variable loot.

You must then replace the value from the vault by a message of your choice.

I sure hope you didn't do anything stupid, Jackie.
― Ray Nicolette