JavaScript驚くべき演算子

JavaScript驚くべき演算子
皆さんこんにちは.
このチュートリアルでは、初心者の開発者のほとんどが知っている非常に便利で時間を節約する演算子について3つの驚くべき演算子を議論するつもりです.
3演算子は

Norlish Coalescing演算子(??)

論理的なNULL割り当て(??=)

オプション連鎖演算子(?)

私たちは、これらの演算子の各々を、よりよく理解するための例のいくつかと一つずつ話し合うつもりです.

1 .偽合体演算子(??)

syntax:
a??b

• If a is defined then the output will be a
• if a is not defined/ Nullish (NULL or UNDEFINED) then the output will be b

In other words, Nullish Coalescing Operator(??) returns the first argument if it is NOT null or undefined. Otherwise returns second argument

Examples:

let a=NULL
console.log(a??50) //50
console.log(a) //NULL

let a=10
let c=30
console.log(a??b??c??d) //10
//gives output, the first defined value

2 .論理ヌル割り当て(??=)

syntax:
a ??= b
the above syntax is equivalent to a ?? (a=b)

• if a is not NULLISH (Null or Undefined), then output will be a
• if a is NULLISH, then output will be b, and value of b is assigned to a

example:

let a=NULL
console.log(a??=50) //50
console.log(a) //50
//compare the output of a from the previous example.

3 .任意の連鎖演算子(?)

syntax:
obj ?. prop

• is similar to obj.prop if the value of obj exist,
• otherwise, if value of obj is undefined or null it returns undefined.

By using ?. operator with object instead of using only dot (.) operator , JavaScript knows to implicitly check to be sure that that obj is not null or undefined before attempting to access obj.prop

NOTE: obj can be nested as well like obj . name ?. firstname

example:

let obj= {
   person:{
       firstName:"John",
       lastName:"Doe"
   },

   occupation: {
       compony:'capscode',
       position:'developer'
   },
   fullName: function(){
       console.log("Full Name is: "+ this.person.firstName+" >"+this.person.lastName)
  }
}
console.log(obj . person . firstName) //John
console.log(obj . human . award) //TypeError: Cannot read property 'award' of undefined
console.log(obj ?. human . award) //TypeError: Cannot read property 'award' of undefined
console.log(obj . human ?. award) //undefined
delete obj?.firstName;  // delete obj.firstName if obj exists
obj . fullName ?. () //logs John Doe
obj ?. fullName() //logs John Doe
obj . fullDetails() // TypeError: obj.fullDetails is not a function
obj ?. fullDetails() // TypeError: obj.fullDetails is not a function
obj.fullDetails ?. () //undefined

summing up these,
The optional chaining ?. syntax has three forms:

1. obj?.prop – returns obj.prop if obj exists, otherwise undefined.
2. obj?.[prop] – returns obj[prop] if obj exists, otherwise undefined.
3. obj.method?.() – calls obj.method() if obj.method exists, otherwise returns undefined.

このようなすべての希望とこのポストは有益であり、あなたの次のプロジェクトに役立つ.
任意のクエリや疑問がある場合は、私たちに連絡して自由に落ちた.
詳細についてはhttps://www.capscode.in/#/をご覧ください
or
Instagramで我々について来てください

私の記事があなたを助けたなら

ありがとう.
capscode