Question

Assume we have a string unknownStr with an unknown value that is not undefined and not null.

Assume we then have this code:

var chrArray = [];
var keyValObject = {};
var keyLength;
for (var i = 0; i < unknownStr.length; i++) { chrArray.push(unknownStr[i]); }
for (var i = 0; i < chrArray.length; i++) { keyValObject[chrArray[i]] = "foo"; }
for (var key in keyValObject) { keyLength = key.length; }

Is it possible that keyLength will ever have a value other than 1?

Answer 1

Yes this is possible and can be demonstrated as follows

Object.prototype.longKey = "foo";

Now all objects will have the property longKey including keyValObject. Because you don’t restrict the key value in the for loop to hasOwnProperty it will eventually see longKey which has a length greater than 1