Conditional spread element

Question

const cond = false  const extraInfo = [   {     a: 11,     b: 25   },   {     a: 12,     b: 34   },   {     a: 1,     c: 99   } ]  const userInfo = [   {     z: 8   },   {     z: 10   },   ...(cond && extraInfo) ] 

When cond is true, I want both extra and user info.

When cond is false, only userInfo is needed.

The issue is when cond is false, I get

TypeError: (intermediate value)(intermediate value)(intermediate value)[Symbol.iterator] is not a function

My understanding is that I am not allowed to use a boolean as a spread element, in this case ...false.

But ...( cond ? extraInfo : {} ) doesn't seem to work either.

What is going on?

Answer 1

Just make it

...(cond ? extraInfo : []) 

Demo with true

var cond = true;    var extraInfo = [    {      a: 11,      b: 25    },    {      a: 12,      b: 34    },    {      a: 1,      c: 99    }  ];    var userInfo = [    {      z: 8    },    {      z: 10    },    ...(cond ? extraInfo : [])  ];    console.log( userInfo );

Demo with false

var cond = false;    var extraInfo = [    {      a: 11,      b: 25    },    {      a: 12,      b: 34    },    {      a: 1,      c: 99    }  ];    var userInfo = [    {      z: 8    },    {      z: 10    },    ...(cond ? extraInfo : [])  ];    console.log( userInfo );

Answer 2

Conditionally spread an entity to Object

console.log(   {      name: 'Alex',     age: 19,     ...(true && { city: 'Kyiv' }),     ...(false && { country: 'Ukraine' })   } )   // { name: 'Alex', age: 19, city: 'Kyiv' }  

Conditionally spread an entity to Array

 console.log(   [     'Dan',     'Alex',     ...(true ? ['Robin'] : [])   ] )  // [ 'Dan', 'Alex', 'Robin' ]