Lets say some function can return Blob, String or plain Object, depending on the use case. After the value is returned I want to implement different code for each type. How can I tell them apart?
For simplification I commented the 3 options that can return from the manage function, but this is the way I manage it right now:
const manage = () => {
return new Blob([JSON.stringify({ myKey: 'myValue'})], { type: 'application/json' });
// return { error: 'my error msg' };
// return 'lets say this is base64 string';
};
const result: Blob | { error: string } | string = manage();
switch(Object.prototype.toString.call(result)) {
case "[object Blob]":
console.log('Blob case runs...');
break;
case "[object String]":
console.log('String case runs...');
break;
case "[object Object]":
console.log('Object case runs...');
break;
default: console.log('Default case runs...');
};<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.production.min.js"></script>Obviously I am not happy with the "Object.prototype.toString.call" solution. Also some answers suggested to use the "instance of" operator, but this is also not a reliable option in my situation.
Can someone point me in a better direction?
you can just return the type of data and the data in the manage function
const manage = () => {
return {
type: "Bolb",
data: new Blob([JSON.stringify({ myKey: 'myValue'})], { type: 'application/json' });
}
return {type: "error", error: 'my error msg' };
return {type: "string", message: 'lets say this is base64 string'};
};
const result: Object = manage();
switch(result.type) {
case "Bolb":
console.log('Blob case runs...');
break;
case "string":
console.log('String case runs...');
break;
case "error":
console.log('Object case runs...');
break;
default: console.log('Default case runs...');
};