I can't find any example on MDN. I came up with this,
const simpleMap = new WeakMap()
const simpleObject = {};
simpleMap.set(simpleObject, "A Value");
if(simpleMap.has(simpleObject)) {
  simpleMap.set(simpleObject, "A New Value");
 }
Is this way correct or shall I delete the key first before doing this?
                        
You could update directly.