typescript double question mark code example

Example 1: double question mark javascript

//Similar to || but only returns the right-hand operand if the left-hand is null or undefined
0 ?? "other" // 0
false ?? "other" // false
null ?? "other" // "other"
undefined ?? "other" // "other"

Example 2: typescript double question mark

A = A ?? B;
//it is the same as
if( null != A )
    A = A;
else
    A = B;