the following is the code I wrote while debugging, but I reported an error
function fn (x: number | string,y: number | string){
return x+y
}but it"s okay to write like this
function fn (x: number,y: string){
return x+y
}the following way of writing will also report an error
function fn (x: number | string,y: number){
return x+y
}in my understanding, the + operation is the common operation symbol of number and string. Why does it report an error?
bug.. Bar
perhaps the right thing to do is to expand union and find that there can be a + operation when x is number or string, but it seems that tsc did not do so.
try defining the type of return value
seems to be designed on purpose issues/29098
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