JavaScript
CHALLENGE
const handler = {
get(target, prop, receiver) {
if (!(prop in target)) {
return `no ${String(prop)}`;
}
return Reflect.get(target, prop, receiver);
},
set(target, prop, value) {
if (typeof value === 'number' && value < 0) {
throw new RangeError('negative');
}
return Reflect.set(target, prop, value);
}
};
const obj = new Proxy({ a: 1, b: 2 }, handler);
obj.c = 10;
console.log(obj.a, obj.c, obj.missing, obj.hasOwnProperty('a'));
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