SyntaxError: Invalid or unexpected token (V8-based)SyntaxError: identifier starts immediately after numeric literal (Firefox)SyntaxError: No identifiers allowed directly after numeric literal (Safari)

The names of variables, calledidentifiers, conform to certain rules,which your code must adhere to!

A JavaScript identifier must start with a letter, underscore (_), or dollar sign ($).They can't start with a digit! Only subsequent characters can be digits (0-9).

Variable names can't start with numbers in JavaScript. The following fails:

const 1life = "foo";// SyntaxError: identifier starts immediately after numeric literalconst foo = 1life;// SyntaxError: identifier starts immediately after numeric literal

You will need to rename your variable to avoid the leading number.

const life1 = "foo";const foo = life1;

In JavaScript, there is a syntactic peculiarity when calling properties or methods on numbers. If you want to call a method on an integer, you cannot immediately use a dot after the number because the dot is interpreted as the start of a decimal fraction, causing the parser to see the method's name as an identifier immediately after a number literal. To avoid this, you need to either wrap the number in parentheses or use a double dot, where the first dot is a decimal point for the number literal and the second dot is the property accessor.

alert(typeof 1.toString())// SyntaxError: identifier starts immediately after numeric literal

Correct ways to call methods on numbers:

// Wrap the number in parenthesesalert(typeof (1).toString());// Add an extra dot for the number literalalert(typeof 2..toString());// Use square bracketsalert(typeof 3["toString"]());

• Lexical grammar
• Grammar and types guide