Optional.js

-------------|---------|----------|---------|---------|-------------------
File         | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
-------------|---------|----------|---------|---------|-------------------
All files    |     100 |      100 |     100 |     100 | 
Optional.js  |     100 |      100 |     100 |     100 | 
-------------|---------|----------|---------|---------|-------------------

coverage 100%!!

demo

const obj = {
    a:[1,2,{a:"aa"}],
    b:{a:"ba",b:undefined}
}

Optional(obj).getOrElse("a[0]","none") // 1
Optional(obj).getOrElse("a[1]","none") // 2
Optional(obj).getOrElse("a[2]","none") // {a:"aa"}
Optional(obj).getOrElse("a[2].a","none") // "aa"
Optional(obj).getOrElse("b.b","none") // "none"

Optional(obj).getOrElse("a[3]","none") // "none"
Optional(obj).getOrElse("a[3]",(obj)=>"none") // "none"


const user = {
    name:"uma",
    action:{
        login:()=>"login_proc"
    }
}

Optional(user).getOrElse("action.login()","none") // "login_proc"
Optional(user).getOrElse("action.logout()","none") // "none"



const array = [
    1,2,3,undefined,NaN,null,4,5
]

[...Optional(array)].join("") // "12345"

for(const safeItem of Optional(array)){
    console.log(safeItem) // 1 2 3 4 5
}

const obj2 = {
    a:1,b:2,c:3,d:undefined,e:NaN,f:null,g:4,i:5
}

[...Optional(obj2)].join("") // "12345"

for(const safeItem of Optional(obj2)){
    console.log(safeItem) // 1 2 3 4 5
}

document

@see src/Optional.test.js

npm

coming soon

test run

git clone {this} 
npm install
npm test

memo

reference sites
    https://qiita.com/riversun/items/6c30a0d0897194677a37