Денис

<form>
  <select name="dropdown">
    <option value="opt_1">Opt 1</option>
    <option value="opt_2" selected>Opt 2</option>
    <option value="opt_3">Opt 3</option>
  </select>
  <input type="text" name="some_text" value="Text">
  <input type="checkbox" name="checkbox_1" value="checked" checked>
  <input type="checkbox" name="checkbox_2" value="not checked">
  <input type="radio" name="radio_group" value="not checked">
  <input type="radio" name="radio_group" value="checked" checked>
  <input type="radio" name="radio_group" value="not checked">
  <textarea name="bigtext">Lorem ipsum dolor sit amet, consectetur adipisicing elit. Reprehenderit, ab tempora voluptate assumenda!</textarea>
</form>
<div id="demo"></div>

var result = [];
[].forEach.call(document.querySelector('form').elements, function(el) {
  if (['checkbox', 'radio'].indexOf(el.type) === -1 || el.checked) {
    result.push(el.name + ' > ' + el.value);
  }
});
demo.innerHTML = result.join('<br>');

$('button').on('click', function(){
    if ($.trim($('input').val()) === '') {
        // в текстовом поле нет ни одного символа
    }
});

$.ajaxSetup({
    beforeSend: function(jqXHR, settings) {
        console.log(settings.data);
    }
});

$.ajaxSetup({
    beforeSend: function(jqXHR, settings) {
        if ('http://site.com'.indexOf(settings.url) !== -1) {
            console.log(settings.data);
        }
    }
});

var root = $('<div class="districts" />'),
    box, child;
for (var k in data) {
    if (data.hasOwnProperty(k)) {
        box = $('<div class="popup" />');
        child = $('<div calss="' + k + '" />').appendTo(box);
        for (var i in data[k].img) {
            if (data[k].img.hasOwnProperty(i)) {
                $('<img src="/img/' + k + '/' + data[k].img[i].name + '.png" />').appendTo(child);
            }
        }
        box.appendTo(root);
    }
}

$('body').append(root); // выводим на экран
// (!) при этом, выводим один раз, а не мучаем DOM на каждой итерации

<div class="districts">
    <div class="popup">
        <div calss="test">
            <img src="/img/test/01.png">
            <img src="/img/test/02.png">
            <img src="/img/test/03.png">
        </div>
    </div>
    <div class="popup">
        <div calss="test2">
            <img src="/img/test2/01.png">
            <img src="/img/test2/02.png">
            <img src="/img/test2/03.png">
        </div>
    </div>
    <div class="popup">
        <div calss="test3">
            <img src="/img/test3/01.png">
            <img src="/img/test3/02.png">
            <img src="/img/test3/03.png">
        </div>
    </div>
    <div class="popup">
        <div calss="test4">
            <img src="/img/test4/01.png">
            <img src="/img/test4/02.png">
            <img src="/img/test4/03.png">
        </div>
    </div>
</div>

<div>
    <label>
        <input type="hidden" name="stand[3]">3
    </label>
    <label>
        <input type="hidden" name="stand[1]">1
    </label>
    <label>
        <input type="hidden" name="stand[2]">2
    </label>
</div>
<div>
    <img src="http://automated-testing.info/images/emoji/apple/smile.png" alt="">
    <img src="http://radar.techcabal.com/images/emoji/apple/grin.png" alt="">
    <img src="http://www.stickees.com/files/emoticons/emojicons/148-happy-smile.png" alt="">
</div>
<button>GO!</button>

var but = $('button'),
    inp = $('[name^="stand"]');
$('img').draggable({
    revert: 'invalid'
});
$('label').droppable({
    accept: function() {
        return $.trim($('input', this).val()) === '';
    },
    tolerance: 'fit',
    drop: function(e, ui) {
        $('input', this).val(ui.draggable.attr('src'));
        $(ui.draggable).draggable('disable');
        var hasEmpty = inp.filter(function() {
            return $.trim($(this).val()) === '';
        }).length;
        but[hasEmpty ? 'hide' : 'show']();
    }
});

but.on('click', function() {
    $.ajax({
        url: '/echo/html/',
        type: 'POST',
        data: inp,
        success: function(data) {}
    });
});

print_r($_POST['stand']);
Array (
    [1] => path/to/img1.png
    [2] => path/to/img2.png
    [3] => path/to/img3.png
)

var myselect = document.getElementById('myselect'),
    selIndx = 0;
myselect.addEventListener('focus', function() {
    selIndx = this.selectedIndex;
    this.options[this.options.length - 1].selected = true;
}, false);
myselect.addEventListener('blur', function() {
    this.selectedIndex = selIndx;
}, false);
myselect.addEventListener('change', function() {
    selIndx = this.selectedIndex;
    this.blur();
}, false);

var sel = document.querySelector('select');
sel.options[0].textContent = 'от ' + sel.options[0].textContent;
sel.addEventListener('change', function(){
	var curIndex = this.selectedIndex;
    [].forEach.call(this.options,function(opt, i){
    	if(i === curIndex) {
        	opt.textContent = 'от ' + opt.textContent;
        } else {
        	opt.textContent = opt.textContent.replace(/[^\d]+/,'');
        }
    });
});

[].forEach.call(this.options,function(opt, i){
    opt.textContent =  i === curIndex ? 'от ' + opt.textContent : opt.textContent.replace(/[^\d]+/,'');
});

$('#first').insertAfter('#second');
// или аналогично
// $('#second').insertBefore('#first');

showFirstLastLetter: function(){
    	this.guessLetterInput.val(this.wrd.letters[0].letter);
      	this.guessForm.trigger('submit');
        this.guessLetterInput.val(this.wrd.letters[this.wrd.totalLetters-1].letter);
      	this.guessForm.trigger('submit');        
},

;(function($){
	$.fn.fadeInDelay = function(){
    	var init = function(){
        	$(this).hide().delay($(this).data('delay')).fadeIn();
        };
    	return this.each(init);
    };
}(jQuery));
$('div').fadeInDelay();

$(function() {
    if ($(window).width() < 768) {
        var iconset = $('.iconset-phone');
        $(window).on('scroll', function() {
            iconset[$(this).scrollTop() > 0 ? 'slideUp' : 'slideDown']();
        });
    }
});

<div data-hint="Какой-то текст к div-у 1">1</div>
<div data-hint="Какой-то текст к div-у 2">2</div>
<div data-hint="Какой-то текст к div-у 3">3</div>
<div id="hint"></div>

div[data-hint] {
    display: inline-block;
    width: 150px;
    height: 150px;
    margin: 15px;
    border: 1px solid #900;
}
#hint {
    display: none;
    position: absolute;
    padding: 5px;
    margin: -15px auto auto 10px;
    border-radius: 5px;
    box-shadow: 0 0 1px 2px rgba(0,0,0,.3);
    background-color: #fff;
    z-index: 100500;
}

var hint = $('#hint');
$('div[data-hint]').on({
    mouseenter: function(){
        hint.text($(this).data('hint')).show();
    },
    mouseleave: function(){
        hint.hide();
    },
    mousemove: function(e){
        hint.css({top: e.pageY, left: e.pageX});
    }
});

<script>
var txt = $('p').clone().children().remove().end().text();
console.log(txt); // 1
</script>