multiply all numbers in an array javascript
The cause is already known. Here's an alternative - using Array.reduce for your method:
console.log( [1, 2, 3].reduce( (a, b) => a * b ) );
console.log( Array.from( {length: 20} )
.map( (v, i) => i + 1 )
.reduce( (a,b) => a * b )
.toLocaleString());
// for empty arrays, use some initial value
const arr = [];
if (arr.reduce( (a, b) => a * b, -1 ) === -1) {
console.error(`The given array ${arr} is empty`);
}