RegExp，单词之间仅允许一个空格

Question

I'm trying to write a regular expression to remove white spaces from just the beginning of the word, not after, and only a single space after the word.

Used RegExp:

var re = new RegExp(/^([a-zA-Z0-9]+\s?)*$/);

Test Exapmle:

1) wordX[space] - Should be allowed 
2) [space] - Should not be allowed 
3) WrodX[space][space]wordX - Should be allowed 
4) WrodX[space][space][space]wordX - Should be allowed 
5) WrodX[space][space][space][space] - Should be not be allowed 
6) WrodX[space][space] - Allowed with only one space the moment another space is entered **should not be allowed** 

Answer 1

Try this one out:

^\s*\w+(\s?$|\s{2,}\w+)+

Test cases ("s added for clarity):

"word"         - allowed (match==true)
"word "        - allowed (match==true)
"word  word"   - allowed (match==true)
"word   word"  - allowed (match==true)
" "            - not allowed (match==false)
"word  "       - not allowed (match==false)
"word    "     - not allowed (match==false)
" word"        - allowed (match==true)
"  word"       - allowed (match==true)
"  word "      - allowed (match==true)
"  word  word" - allowed (match==true)

See demo here.

Answer 2

Try this:

var re = /\S\s?$/;

This matches a non-space followed by at most one space at the end of the string.

BTW, there's no need to use new RegExp when you're providing a regexp literal. That's only needed when converting a string to a RegExp.

Answer 3

Try this regex

/^(\w+)(\s+)/

and your code:

result = inputString.replace(/^(\w+)(\s+)?/g, "$1");

Answer 4

try to use code that i am giving you and implement with javascript, i hope it will for you fine HTML Code

<input type="test" class="name" />

Javascript Code:

$('.name').keyup(function() {
    var $th = $(this);
    $th.val($th.val().replace(/(\s{2,})|[^a-zA-Z']/g, ' '));
    $th.val($th.val().replace(/^\s*/, ''));
    });

This code does not allow more than one spaces between characters or words. Check here JsFiddle Link .