JavaScript SyntaxError

Question

I'm learning JavaScript by reading Eloquent JavaScript. I'm running my code on the console provided by the book's website. I'm getting a SyntaxError : Unexpect Identifier from the following bit of code. Please help.

function absolute (n){
  if (n < 0)
    return -n;
  else
    return n;
}  

function average(x, y){
  return (x + y) / 2;
}


function isGoodEnough(x, guess){
  return (absolute(x - guess) < 0.0001);
}

function maybe(x, guess){
  if isGoodenough(x, guess){
    return guess;
  }
  else{
    return maybe(x, average(x, x/guess));
  }
}

function sqrt(x){
  return maybe(x, 1);
}

You're missing parentheses around the if isGoodEnough(x, guess) in the maybe function. — Andrew Whitaker
– Andrew Whitaker, Commented Oct 17, 2013 at 16:00
You should use return -1*n, not return -n. Also, JSlint is your friend. — Bucket
– Bucket, Commented Oct 17, 2013 at 16:01
This question and its answers suck... They're only useful for this very specific question. A debugging tutorial would be much more helpful to future visitors. — Rob W
– Rob W, Commented Oct 17, 2013 at 16:02

Barmar · Accepted Answer · 2013-10-17 16:01:20Z

3

You're missing the parentheses in your if statement:

if (isGoodEnough(x, guess)) {

You also misspelled the function name, and that will cause a different error.

answered Oct 17, 2013 at 16:01

Barmar

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steveukx · Accepted Answer · 2013-10-17 16:00:45Z

2

if isGoodenough(x, guess){ is missing the parentheses: if(isGoodenough(x, guess)){

answered Oct 17, 2013 at 16:00

steveukx

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Comments

Default · Accepted Answer · 2013-10-17 16:00:04Z

1

isGoodEnough is mispelled in the maybe function.

function maybe(x, guess){
  if isGoodenough(x, guess){
    return guess;
  }
  else{
    return maybe(x, average(x, x/guess));
  }
}

answered Oct 17, 2013 at 16:00

Default

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2 Comments

Rob W Over a year ago

This is true, but misspellings will cause a ReferenceError at most, not a SyntaxError.

user1937976 Over a year ago

If fixed the brackets and the spelling error. Now I'm exceeding the maximum call stack. I'll just go rewrite it with a loop.

exussum · Accepted Answer · 2013-10-17 16:00:59Z

1

You missed the brackets

 if isGoodEnough(x, guess){
    return guess;
  }

should be

 if (isGoodEnough(x, guess)){
    return guess;
  }

answered Oct 17, 2013 at 16:00

exussum

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Comments

RichieHindle · Accepted Answer · 2013-10-17 16:01:15Z

1

You need parentheses around this if condition:

function maybe(x, guess) {
    if (isGoodEnough(x, guess)) {   // Note extra parentheses
        ...

(You've also misspelled "isGoodEnough" here.)

answered Oct 17, 2013 at 16:01

RichieHindle

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Comments

Ignacy Debicki · Accepted Answer · 2013-10-17 16:20:43Z

0

you need to put parantheses around the if conditions and else as well. Also use brackets to test statments after if statments. should look like

 function absolute (n){
  if (n < 0){
    return -n;
    }
  else {
    return n;
    }
  }  

 function average(x, y){
   return (x + y) / 2;
   }


 function isGoodEnough(x, guess){
   return (absolute(x - guess) < 0.0001);
   }

 function maybe(x, guess){
  if (isGoodEnough(x, guess)){
     return guess;
     }
  else{
     return maybe(x, average(x, x/guess));
     }
 }

  function sqrt(x){
   return maybe(x, 1);
  }

answered Oct 17, 2013 at 16:20

Ignacy Debicki

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