javascriptconditional-operatoriterableexpansion

Expansion with conditional ternary operator

Simple question: Is there a way to use an expansion inside a conditional statement using the ternary operator?

const a = 1, b = 2;

// Works
console.log(...[ a, b ]);

// Works
console.log(...(a ? [ a, b ] : [ 'Not found' ]));

// Doesn't work
console.log(a ? ...[ a, b ] : 'Not found');

Solution

  • Unfortunately this isn’t currently possible. The … spread syntax, like its name tells us, is a part of the syntax of the language and not a ‘normal’ operator that deals with expressions (à la + or typeof). The ternary operator needs expressions after the ? and :, so you can’t use the syntax in those spots.

    You’ll have to do e.g.

    condition
    ? console.log(…)
    : console.log(…)