react typescript object is possible undefined-CodePudding

In my react typescript project I am trying to update a value in my redux state.

When I try to update the x1.quantity, I get the following error. (VS code puts a red line under x1)

Object is possibly 'undefined'

mySecondTest: (state, action: PayloadAction<TradeData>) => {
  console.log("this is mySecondTest reducer");
  console.log(action.payload);
  console.log(state.trades);

  const x1 = state.trades.find((item) => item.bbsymbol === "ADH2 Curncy");
  console.log("this is x1");
  if (x1.quantity !== undefined) {
    x1.quantity = 999;
  }

Can someone show me the proper way to handle this?

CodePudding user response：

There is an error because find can return undefined if no value was found. And to fix this there are many ways!

Using optional chaining:
```
if (x1?.quantity !== undefined) {
```
Using && short-circuiting:
```
if (x1 && x1.quantity !== undefined) {
```
Using an assertion (! - only use if you are sure it can't be undefined):
```
if (x1!.quantity !== undefined) {
```