javascript match() error

I'm trying to count # of lines of a pre element and I'm using this:

var numlines = $('#mypreelement').text().match(/\n\r?/g).length + 1;

it works, but in some situations I get a error

Error: $('#mypreelement').text().match(/\n\r?/g) is null

this only happens on开发者_Python百科 certain pages, but these pages don't have anything different from the ones on which it works, besides content of course...

Why?

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That means it couldn't match any of them, and null does not have a length property.

So try this...

if (var lines = $('#mypreelement').text().match(/\n\r?/g) != null) {
   var linesLength = lines.length + 1;
}

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MDC RegExp Match

If the regular expression includes the g flag, the method returns an Array containing all matches. If there were no matches, the method returns null.