正则表达式强制第一个字符后的单个空格

Question

How do I force a space after first character as user types. I just need only one space after first character (no spaces allowed before first one). After first character and space there can be upto 40 characters.

I found this so far, but does not fit my needs

$('.singleSpace').keyup(function() {
  var foo = $(this).val().split(" ").join(""); // remove hyphens
  if (foo.length > 0) {
    foo = foo.match(new RegExp('.{1}', 'g')).join(" ");
  }
  $(this).val(foo);
});

sample

Answer 1

I don't know why you want to do this but to remove spaces you can use this :

var str = $(this).val().replace(" ", "");

And for add a space after first character :

var str = $(this).replace("^(.)(.*)$", "$1 $2");

Answer 2

Do you need the regex?

$('.singleSpace').keyup(function() {
  var $el = $(this);
  var val = $el.val();
  if (val.length === 1) {
    $el.val(val + ' ');
  }
});

Answer 3

You can use this code :

$('.singleSpace').keyup(function() {
    var foo = $(this).val().replace(/^( *)([^ ] *)(.*)/g, function(_,b,c,d){
        return $.trim(c) + ' ' + d.replace(/ /g, '').slice(0,40);
    })

    $(this).val(foo)
});

The only problem is the cursor position. If you type while the cursor is not at the end, the cursor will always return the the end.

See for yourself : http://jsfiddle.net/S3gJL/2/

I would suggest you tu put that function in a blur event instead, but that can be annoying aswell.

Your request is not simple at all. There is a lot of variation, users can copy paste, select and delete. It is hard to prevent everything.

The code provided above block a lot of detour (only thing that doesn't block is the right-click paste and maybe other things i'm not think of ), but with the cost stated above. You might wanna search for a plugin or hire someone to develop a good system.

---

Edit 1

Remove the authorisation to write space after the first one.

---

Edit 2

For the cursor position here the fix :

$('.singleSpace').keyup(function() {
    var foo = this.value.replace(/^( *)([^ ] *)(.*)/g, function(a,b,c,d,e){
        return $.trim(c) + ' ' + d.replace(/ /g, '').slice(0,40);
    })

    var carretPos = doGetCaretPosition(this)

    carretPos += foo.length - this.value.length

    this.value = foo;

    setSelectionRange(this, carretPos, carretPos)
});


//Code taken from
// http://stackoverflow.com/questions/17858174/set-cursor-to-specific-position-on-specific-line-in-a-textarea
function setSelectionRange(input, selectionStart, selectionEnd) {
    if (input.setSelectionRange) {
        input.focus();
        input.setSelectionRange(selectionStart, selectionEnd);
    }
    else if (input.createTextRange) {
        var range = input.createTextRange();
        range.collapse(true);
        range.moveEnd('character', selectionEnd);
        range.moveStart('character', selectionStart);
        range.select();
    }
}

//Code taken from
// http://stackoverflow.com/questions/2897155/get-cursor-position-in-characters-within-a-text-input-field
function doGetCaretPosition (oField) {

    // Initialize
    var iCaretPos = 0;

    // IE Support
    if (document.selection) {

        // Set focus on the element
        oField.focus ();

        // To get cursor position, get empty selection range
        var oSel = document.selection.createRange ();

        // Move selection start to 0 position
        oSel.moveStart ('character', -oField.value.length);

        // The caret position is selection length
        iCaretPos = oSel.text.length;
    }

    // Firefox support
    else if (oField.selectionStart || oField.selectionStart == '0')
        iCaretPos = oField.selectionStart;

    // Return results
    return (iCaretPos);
}

FIDDLE

Answer 4

The var is done to deal with the cursor position

var val="";
$('.singleSpace').keyup(function() {
    var ele = $(this)[0];
    var foo = ele.value;
    if(val==foo){return false}
    var startPos = ele.selectionStart;
    var endPos = ele.selectionEnd;
    if(event.keyCode==8){
        var diff=endPos-startPos;
        startPos-=diff;
        endPos-=diff;
    }
    foo = foo.replace(new RegExp('( )','g'),'');
    foo = foo.replace(new RegExp('^ *(.) *(.*?)'),'$1 $2');
    val=foo;
    ele.value=foo;
    ele.selectionStart=startPos;
    ele.selectionEnd=endPos;
});

This is the regExp you want: *(.) *(.*?) and you want to use .replace not match

Demo