How do I split a string by whitespace and ignoring leading and trailing whitespace into an array of words using a regular expression?

问题

I typically use the following code in JavaScript to split a string by whitespace.

"The quick brown fox jumps over the lazy dog.".split(/\s+/);
// ["The", "quick", "brown", "fox", "jumps", "over", "the", "lazy", "dog."]

This of course works even when there are multiple whitespace characters between words.

"The  quick brown fox     jumps over the lazy   dog.".split(/\s+/);
// ["The", "quick", "brown", "fox", "jumps", "over", "the", "lazy", "dog."]

The problem is when I have a string that has leading or trailing whitespace in which case the resulting array of strings will include an empty character at the beginning and/or end of the array.

"  The quick brown fox jumps over the lazy dog. ".split(/\s+/);
// ["", "The", "quick", "brown", "fox", "jumps", "over", "the", "lazy", "dog.", ""]

It's a trivial task to eliminate such empty characters, but I'd rather take care of this within the regular expression if that's at all possible. Does anybody know what regular expression I could use to accomplish this goal?

回答1:

If you are more interested in the bits that are not whitespace, you can match the non-whitespace instead of splitting on whitespace.

"  The quick brown fox jumps over the lazy dog. ".match(/\S+/g);

Note that the following returns null:

"   ".match(/\S+/g)

So the best pattern to learn is:

str.match(/\S+/g) || []

回答2:

" The quick brown fox jumps over the lazy dog. ".trim().split(/\s+/);

回答3:

Instead of splitting at whitespace sequences, you could match any non-whitespace sequences:

"  The quick brown fox jumps over the lazy dog. ".match(/\S+/g)

回答4:

Not elegant as others code but very easy to understand:

    countWords(valOf)
    {
        newArr[];
        let str = valOf;
        let arr = str.split(" ");

        for (let index = 0; index < arr.length; index++) 
       {
           const element = arr[index];
           if(element)
           {
              this.newArr.push(element);
           }
       }
       this.NumberOfWords = this.newArr.length;

       return this.NumberOfWords;
   }

来源：https://stackoverflow.com/questions/14912502/how-do-i-split-a-string-by-whitespace-and-ignoring-leading-and-trailing-whitespa

标签

javascript

regex

string

whitespace

removing-whitespace