Difference between ? and ?? in JavaScript/Typescript
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Difference between ? and ?? in JavaScript/Typescript
Hey folks, if you have opened this article that means you are curious about these 2 operators, how they operate, and what's the difference between these two. So without wasting any time, let's jump into details with a code example.
? is Optional Chaining Operator, also commonly named as null checker for objects. Its primary use is to check if an object exists or not.
Example
const user = {
id: 5,
name: "John"
};
console.log(user?.name); //John
console.log(user?.fullName); //undefined, program won't crash.
console.log(user.fullName);
//TypeError: Cannot read property ‘fullName’ of undefined
?? is Nullish Coalescing Operator. It is used to initialize an object/variable if it is undefined or null.
Example
const user = {
id: 5,
name: "",
firstName: null,
lastName: undefined
};
console.log(user.name??"Johnny Depp");// prints ""
console.log(user.firstName??"Johnny");// prints Johnny
console.log(user.lastName??"Depp");// prints Depp
Feel free to add suggestions in the comments.
Thanks. Happy Coding.
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