javascriptLogic errorMedium

Data groups overwriting each other

Time: 0:00

What it should do

groupByLength(words) should group words by their length, so ["ab","cd","x"] gives {"1":["x"],"2":["ab","cd"]}.

What goes wrong

Each group only ever holds one word — ["ab","cd"] gives {"2":["cd"]}, losing "ab".

Hints

This is a logic errors bug

The wrong operator, an inverted condition, a formula the right way round but backwards.