Uncaught TypeError: Cannot read properties of undefined (reading '0') at line 13:1-CodePudding

while working on code ran into some errors on line 13 when the value is undefined and is reading as 0 please how can I solve this

the error message

homepage.js:13 Uncaught TypeError: Cannot read properties of undefined (reading '0')

  const dispatch = useDispatch();
  const danceClass = useSelector((state) => state.class);
  const { classes } = danceClass;

  const [dance, setDance] = useState(
    classes[0] ? classes[0].slice(0, 3) : [],
  );

CodePudding user response：

If your danceClass object doesn't have a classes property, then classes will be undefined and classes[0] will produce the error you're seeing.

Try using optional chaining instead

const [dance, setDance] = useState(classes?.[0]?.slice(0, 3) ?? []);

The above will also work if classes is an empty array.

CodePudding user response：

Because the classes is undefined. You should check like

classes ? classes[0]?.slice(0,3) : []