Array.from has a second argument

This post is part of my Today I learned series in which I share all my learnings regarding web development.

This post is a rather quick one. I followed a Twitter conversation by Surma from Google and Andrea Giammarchi in which Andrea mentionied that Array.from accepts a second argument. I heard this fact a few times before but always forgot it again. Let's hope I'll remember this fact the next time I want to create and transform an Array out of something.

console . log ( Array . from ( [ 1 , 2 , 3 ] , x => x + x ) ) ;

The snippet they discussed showed functionality to call a callback X times.

Array . from ( { length } , ( ) => callback ( ) ) Array . from ( { length : 7 } , ( v , i ) => String . fromCodePoint ( 129300 + Math . floor ( Math . random ( ) * 20 ) ) ) ;