JSFiddle - React, Tailwind, and code Playground

by ivanovsuper

HTML

<link rel="stylesheet" href="http://aubakirovalexandr.com/style.css">
<div id="forma">
  <table>
    <tr>
      <form name="lessonForm" method="post" action="mail.php">
        <td>
          <p class="formhead">Выберите количество занятий</p>
          <div class="kolvo">
            <a onClick="document.getElementById('lessons').value++; return true;"><div class="plus"></div></a>
            <input type="text" size="3" name="lessons" id="lessons" value="0">
            <a onClick="document.getElementById('lessons').value--; return true;"><div class="minus"></div></a>
          </div>
          <input class="raschet" type="button" value="Посчитать" onClick="lessonCount(lessonForm)">
          <br />
          <div class="price-box">Цена:
            <input type="text" size="2" class="price" name="m45" value="0" />p. за 45 Минут
            <div class="choise">
                <input type='radio' name='chb[]' id="r45" /><label for="r45">Выбрать</label></div>
            <br />Цена:
            <input type="text" size="2" class="price" name="m60" value="0" />p. за 60 Минут
            <div class="choise">
                <input type='radio' name='chb[]' value="Выбрано 60 минут" id="r60" /> <label for="r60">Выбрать</label></div>
            <br />Цена:
            <input type="text" size="2" class="price" name="m90" value="0" />p. за 90 Минут
            <div class="choise">
                <input type='radio' name='chb[]' id="r90" value="Выбрано 90 минут" /><label for="r90">Выбрать</label></div>
            <br />
          </div>
          <br />
          <div id="skidka">Ваша сидка:
            <input type="text" class="dis" name="dis" value="0" />
          </div>
          <br/>
        </td>
        <td>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td>
        <td align="right">Ваше имя:
          <input type="text" name="name" class="name" />
          <br/>Эл.почта:
          <input type="text" name="email" class="email" />
          <br/>Логин в Скайп:
          <input...

JavaScript

function lessonCount(lessonForm) {
    var num = lessonForm.lessons.value;
    if (num < 0) {
        lessonForm.m45.value = 0;
        lessonForm.m60.value = 0;
        lessonForm.m90.value = 0;
        lessonForm.dis.value = "0%";
    }
    if (num > 0 && num < 5) {
        lessonForm.m45.value = 300 * num;
        lessonForm.m60.value = 400 * num;
        lessonForm.m90.value = 550 * num;
        lessonForm.dis.value = "0%";
    }
    if (num > 4 && num < 10) {
        lessonForm.m45.value = 282 * num;
        lessonForm.m60.value = 376 * num;
        lessonForm.m90.value = 517 * num;
        lessonForm.dis.value = "6%";
    }
    if (num > 9 && num < 20) {
        lessonForm.m45.value = 276 * num;
        lessonForm.m60.value = 368 * num;
        lessonForm.m90.value = 506 * num;
        lessonForm.dis.value = "8%";
    }
    if (num > 19) {
        lessonForm.m45.value = 270 * num;
        lessonForm.m60.value = 360 * num;
        lessonForm.m90.value = 495 * num;
        lessonForm.dis.value = "10%";
    }
    document.getElementById('r45').value = lessonForm.m45.value;
    document.getElementById('r60').value = lessonForm.m60.value;
    document.getElementById('r90').value = lessonForm.m90.value;
}