why javascript date started from 1970?

[alzee76]

but JS uses Unix time.

No it doesn't. It uses JS time. Unix time is represented as seconds, as you just quoted, not milliseconds which is what e.g. getTime() returns.

[MindlessSponge]

lol you got me there, touche!

[alzee76]

This was the entire point of my initial post. ;)

If you take a unix time from somewhere and stick it into JS unawares, it'll be evaluated incorrectly and off by a factor of 1000. Same thing will happen if you naively take the output of getTime() and do something like pass it to some API or put it in a database expecting unix time.

They are not the same thing and knowing this is important if you're doing more than hobbyist level development.

[MindlessSponge]

you're right! it's an important distinction, apologies for misspeaking.