The JavaScript exception "missing variable name" is a common error. It is usually caused by omitting a variable name or a typographic error.
Message
SyntaxError: missing variable name (Firefox)
SyntaxError: Unexpected token '='. Expected a parameter pattern or a ')' in parameter list. (Safari)
Error type
What went wrong?
A variable is missing a name. The cause is most likely a typo or a forgotten variable name.
Make sure that you've provided the name of the variable before the = sign.
When declaring multiple variables at the same time, make sure that the previous lines/declaration does not end with a comma instead of a semicolon.
Examples
Missing a variable name
const = "foo";
It is easy to forget to assign a name for your variable!
const description = "foo";
Reserved keywords can't be variable names
There are a few variable names that are reserved keywords. You can't use these. Sorry :(
const debugger = "whoop";
// SyntaxError: missing variable name
Declaring multiple variables
Pay special attention to commas when declaring multiple variables.
Is there an excess comma, or did you use commas instead of semicolons?
Did you remember to assign values for all your const variables?
let x, y = "foo",
const z, = "foo"
const first = document.getElementById("one"),
const second = document.getElementById("two"),
// SyntaxError: missing variable name
The fixed version:
let x,
y = "foo";
const z = "foo";
const first = document.getElementById("one");
const second = document.getElementById("two");
Arrays
Array literals in JavaScript need square brackets around the values. This won't work:
const arr = 1,2,3,4,5;
// SyntaxError: missing variable name
This would be correct:
const arr = [1, 2, 3, 4, 5];