The JavaScript exceptions "unexpected token" occur once a particular language construct was expected, however one thing else was provided. This may well be a simple typo error.

Exact error messages:

SyntaxError: expected expression, got "x"
SyntaxError: expected property name, got "x"
SyntaxError: expected target, got "x"
SyntaxError: expected rest argument name, got "x"
SyntaxError: expected closing parenthesis, got "x"
SyntaxError: expected '=>' after argument list, got "x"

Some of the examples are the following

Expression expected

for (let i = 0; i < 5,; ++i) {
  console.log(i);
}
// Uncaught SyntaxError: expected expression, got ';'

// Rgiht syntax

for (let i = 0; i < 5; ++i) {
  console.log(i);
}

Not enough brackets

function someFun() {
  if (n > upperBound) || (n < lowerBound) { 
    // some code
  }  else {
    // some code
  }
  // missing brackets
  
 // right syntax
 
 function someFun() {
  	if (n > upperBound) || (n < lowerBound) { 
    	// some code
  	}  else {
    	// some code
  	}
  }