Get key by value

index.js

// Easily get object key by value

const referrerSources = {
    "aws": "AWS Cloud",
    "oudesoft": "Oude software",
    "mvp": "Voordelen van een MVP",
    "corona": "Corona Consult"
}

// Object entries transforms an object into an array with sub arrays with key & value:

// [
//     [ 'aws', 'AWS Cloud' ],
//     [ 'oudesoft', 'Oude software' ],
//     [ 'mvp', 'Voordelen van een MVP' ],
//     [ 'corona', 'Corona Consult' ]
// ]

// Then loop through the array and return the value.
const a = Object.entries(referrerSources).find(referrerSource => referrerSource[1] === "AWS Cloud")?.[0];

console.log(a) // "aws"