“ jsonValueKey() ”

    
let jsonString = '{"name": "nadia", "age": 54, "city": "Mars"}';
let key = "city";

function jsonValueKey(jsonString, key) {
    let json = JSON.parse(jsonString);
    return json[key];
}

// Affichage console
console.log(jsonValueKey(jsonString, key)); // affichera "Mars"
// Affichage HTML
let output = jsonValueKey(jsonString, key);
document.getElementById("output").innerHTML = output;