interface c {
state?: {b: string}
}
const x: c = { state: {b: 'c'}}
console.log(x.state.b)
The code snippet above shows an interface called c with an optional property called state.
Although the property b of the state object is accessed in the code, it results in an error saying Object is possibly 'undefined'. How can this issue be correctly addressed?
The reason for this behavior is that the variable state may not have a defined value, leading to uncertainty for the compiler in certain situations.
To explicitly specify that you are certain of its existence, you can do so by using:x.state!.b
When you want to ensure that an optional field (which is denoted with ?) actually contains a value, you can do so by checking for its presence:
if(y.state !== undefined){
console.log(y.state.b)
}
If you are confident that the optional field holds a value, you can signify it with a !:
console.log(y.state!.b)
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