Javascript Regex \S vs. \s

[CFEmma]

Hello, I have this piece of code I read from a book to remove text nodes that only have white space.

if (node.nodeType == 3 && ! /\S/.test(node.nodeValue)){
   // code to remove the text node
}

Why should we use this:

! /\S/.test(node.nodeValue)

Instead of this?

/\s/.test(node.nodeValue)

[chump2877]

Because the second line of code will return true even if it contains non-space characters, i.e.:

Some text

...would "fail" validation because there is a space between "Some" and "text", so the text node would be removed (when it shouldn't be)

[bullant]

difference between \s and \S

[venegal]

Originally Posted by CFEmma

Why should we use this:

! /\S/.test(node.nodeValue)

Instead of this?

/\s/.test(node.nodeValue)

Just say what they do in plain english, then it should be pretty obvious:

/\s/.test(node.nodeValue)

"The node value must contain whitespace."

! /\S/.test(node.nodeValue)

"The node value must not contain non-whitespace."

So, those are of course two different things. "Containing whitespace" and "containing non-whitespace" are not polar opposites; there are lots of strings that do both. Thus, "containing whitespace" and "not containing non-whitespace" are not the same.

That's the same thing chump2877 said, but I thought it might be easier to understand this way.

[Krupski]

Originally Posted by CFEmma

Hello, I have this piece of code I read from a book to remove text nodes that only have white space.

if (node.nodeType == 3 && ! /\S/.test(node.nodeValue)){
   // code to remove the text node
}

Why should we use this:

! /\S/.test(node.nodeValue)

Instead of this?

/\s/.test(node.nodeValue)

Usually, lowercase "special" patterns mean "match this" while uppercase means "match anything BUT this".

For example, \d matches any digit while \D matches anything BUT a digit.

Or said another way, \d is the same as [0-9] and \D is the same as [^0-9]

In "words", \d means "zero through nine" and \D means "not zero through nine".

In your code above, \S (uppercase S) means "match not whitespace" or "match anything that isn't a whitespace".

\s would mean "match a whitespace".

Hope this makes sense.......

-- Roger

[CFEmma]

Thank you everyone! This makes sense!