remove duplicate spaces from field while typing

gistfile1.js

$('textarea').on('keyup', function() {
    // store cursor location
    var start = this.selectionStart,
        end = this.selectionEnd,
        len = this.value.length;

    // remove duplicate spaces from field
    $(this).val(
        this.value.trim()
        .replace(/(\n\n)+/g, '\n')
        .replace(/(\s\s)+/g, ' ')
    );

    try {
      // calculate new cursor location
      var diff = len - this.value.length;
      start = start-diff; if (start < 0) start = 0;
      end = end-diff; if (end < 0) end = 0;
      // set new cursor position
      this.setSelectionRange(start, end);
    } catch (e) {}
    
});

gistfile2.txt

Initial workout for development / prototype