SyntaxError: Unexpected token
The JavaScript exceptions "unexpected token" occur when a specific language construct was expected, but something else was provided. This might be a simple typo.
Message
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"
Error type
What went wrong?
A specific language construct was expected, but something else was provided. This might be a simple typo.
Examples
Expression expected
For example, when chaining expressions, trailing commas are not allowed.
for (let i = 0; i < 5,; ++i) {
console.log(i);
}
// Uncaught SyntaxError: expected expression, got ';'
Correct would be omitting the comma or adding another expression:
for (let i = 0; i < 5; ++i) {
console.log(i);
}
Not enough brackets
Sometimes, you leave out brackets around if
statements:
function round(n, upperBound, lowerBound){
if(n > upperBound) || (n < lowerBound){
throw 'Number ' + String(n) + ' is more than ' + String(upperBound) + ' or less than ' + String(lowerBound);
}else if(n < ((upperBound + lowerBound)/2)){
return lowerBound;
}else{
return upperBound;
}
} // SyntaxError: expected expression, got '||'
The brackets may look correct at first, but note how the ||
is outside the
brackets. Correct would be putting brackets around the ||
:
function round(n, upperBound, lowerBound){
if((n > upperBound) || (n < lowerBound)){
throw 'Number ' + String(n) + ' is more than ' + String(upperBound) + ' or less than ' + String(lowerBound);
}else if(n < ((upperBound + lowerBound)/2)){
return lowerBound;
}else{
return upperBound;
}
}