SyntaxError: missing ) after condition - JavaScript 编辑

The JavaScript exception "missing ) after condition" occurs when there is an error with how an if condition is written. It must appear in parenthesis after the if keyword.

Message

SyntaxError: Expected ')' (Edge)
SyntaxError: missing ) after condition (Firefox)

Error type

SyntaxError

What went wrong?

There is an error with how an if condition is written. In any programming language, code needs to make decisions and carry out actions accordingly depending on different inputs. The if statement executes a statement if a specified condition is truthy. In JavaScript, this condition must appear in parenthesis after the if keyword, like this:

if (condition) {
  // do something if the condition is true
}

Examples

Missing parenthesis

It might just be an oversight, carefully check all you parenthesis in your code.

if (3 > Math.PI {
  console.log("wait what?");
}

// SyntaxError: missing ) after condition

To fix this code, you would need to add a parenthesis that closes the condition.

if (3 > Math.PI) {
  console.log("wait what?");
}

Misused is keyword

If you are coming from another programming language, it is also easy to add keywords that don't mean the same or have no meaning at all in JavaScript.

if (done is true) {
 console.log("we are done!");
}

// SyntaxError: missing ) after condition

Instead you need to use a correct comparison operator. For example:

if (done === true) {
 console.log("we are done!");
}

See also

• if...else
• Comparison operators

• Making decisions in your code — conditionals