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Message
SyntaxError: missing variable name (Firefox) SyntaxError: Unexpected token = (Chrome)
Error type
What went wrong?
A variable is missing a name. This is likely due to a syntax error in your code. Probably a comma is wrong somewhere or you struggled with coming up with a name. Totally understandable! Naming things is so hard.
Examples
Missing a variable name
var = "foo";
It's tough coming up with good variable names. We all have been there.
var ohGodWhy = "foo";
Reserved keywords can't be variable names
There are a few variable names that are reserverd keywords. You can't use these. Sorry :(
var debugger = "whoop"; // SyntaxError: missing variable name
Declaring multiple variables
Pay special attention to commas when declaring multiple variables. Is there an excess comma? Did you accidentally add commas instead of semicolons?
var x, y = "foo",
var x, = "foo"
var first = document.getElementById('one'),
var second = document.getElementById('two'),
// SyntaxError: missing variable name
The fixed version:
var x, y = "foo";
var x = "foo";
var first = document.getElementById('one');
var second = document.getElementById('two');
Arrays
Array literals in JavaScript need square brackets around the values. This won't work:
var arr = 1,2,3,4,5; // SyntaxError: missing variable name
This would be correct:
var arr = [1,2,3,4,5];