Spaces, new lines, tabs, semicolons

Tip: Recall "Rules of Automatic Semicolon Insertion"

Answer: Yes, it is a valid snippet. JavaScript interpreter will automatically insert semicolons like:

 var 
 foo
 =
 10;
 alert(foo);

Read it for details:
wikipedia.org: Whitespace and semicolons
pdf document: ECMAScript® 2015 Language Specification