Question

How to use union in TypeScript

Answer 1

let U: (string | number);
U = 123;   
U = "ABC"; 

function displayType(U: (string | number)) {
    if (typeof(U) === "number")
        console.log('number')
    else if (typeof(U) === "string")
            console.log('string')
}

displayType(123); 
displayType("ABC"); 
displayType(27184); 
displayType("TypeScript"); 

   
   
   
/*
   
run:
   
"number" 
"string" 
"number" 
"string" 
  
*/

 

 

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