JSFiddle - React, Tailwind, and code Playground

by toddmotto

HTML

<form name="bmi">
  <h1>BMI Calculator</h1>
  <label>
    <input type="text" name="weight" placeholder="Weight (kg)">
  </label>
  <label>
    <input type="text" name="height" placeholder="Height (cm)">
  </label>
  <button type="submit">
    Calculate BMI
  </button>
  <div class="calculation">
    <div>
      BMI calculation: <span class="result"></span>
    </div>
    <div>
      This means you are: <span class="health"></span>
    </div>
  </div>
</form>

SCSS

* {
  box-sizing: border-box;
  -webkit-box-sizing: border-box;
  -moz-box-sizing: border-box;
  font: 300 14px/1.4 'Helvetica Neue', Helvetica, Arial, sans-serif;
}
body {
  background: #596778;
  margin: 0;
  padding: 0;
}
input[type=text] {
  outline: 0;
  width: 100%;
  height: 50px;
  margin-bottom: 25px;
  padding: 0 15px 2px;
  font-size: 17px;
  background: #fff;
  border: 2px solid #ebebeb;
  border-radius: 4px;
  -webkit-box-shadow: inset 0 -2px #ebebeb;
  box-shadow: inset 0 -2px #ebebeb;
  &:focus {
    border-color: #62c2e4;
    outline: none;
    -webkit-box-shadow: inset 0 -2px #62c2e4;
    box-shadow: inset 0 -2px #62c2e4;
  }
}
button[type=submit] {
  width: 100%;
  height: 54px;
  padding: 0;
  font-size: 22px;
  color: white;
  text-align: center;
  text-shadow: 0 1px 2px rgba(0, 0, 0, 0.25);
  background: #f0776c;
  border: 0;
  border-bottom: 2px solid #d76b60;
  border-radius: 5px;
  cursor: pointer;
  -webkit-box-shadow: inset 0 -2px #d76b60;
  box-shadow: inset 0 -2px #d76b60;
}
form {
  overflow: hidden;
  border-radius: 5px;
  padding: 35px;
  margin: 50px;
  position: relative;
  background: #fff;
  h1 {
    margin: -35px -35px 25px;
    padding: 32px 0 25px;
    font-size: 26px;
    font-weight: 300;
    color: #aaa;
    text-align: center;
    text-shadow: 0 1px rgba(255, 255, 255, 0.75);
    background: #f7f7f7;
  }
  &:before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 8px;
    background: #c4e17f;
    border-radius: 4px 4px 0 0;
    background-image: -webkit-linear-gradient(left, #c4e17f, #c4e17f 12.5%, #f7fdca 12.5%, #f7fdca 25%, #fecf71 25%, #fecf71 37.5%, #f0776c 37.5%, #f0776c 50%, #db9dbe 50%, #db9dbe 62.5%, #c49cde 62.5%, #c49cde 75%, #669ae1 75%, #669ae1 87.5%, #62c2e4 87.5%, #62c2e4);
    background-image: -moz-linear-gradient(left, #c4e17f, #c4e17f 12.5%, #f7fdca 12.5%, #f7fdca 25%, #fecf71 25%, #fecf71 37.5%, #f0776c 37.5%, #f0776c 50%, #db9dbe 50%, #db9dbe 62.5%, #c49cde...

JavaScript

(() => {

	const form = document.querySelector('form[name=bmi]');
  
  const getHealthMessage = unit => {
    let healthMessage;
  	if (unit < 18.5) {
      healthMessage = 'considered underweight';
    } else if (unit > 18.5 && unit < 25) {
      healthMessage = 'a healthy weight';
    } else if (unit > 25) {
      healthMessage = 'considered overweight';
    }
    return healthMessage;
  };
  
  const getBMI = (weight, height) => {
  	let newWeight = parseInt(weight, 10);
  	let newHeight = parseInt(height, 10);
    return (newWeight / (newHeight /100 * newHeight / 100)).toFixed(1);
  };
  
  const onSubmit = event => {
  	
    event.preventDefault();
    
    const result = form.querySelector('.result');
    const health = form.querySelector('.health');
    
    const weight = form.querySelector('input[name=weight]').value;
    const height = form.querySelector('input[name=height]').value;
    
    const bmi = getBMI(weight, height);
    
    result.innerHTML = bmi;
    health.innerHTML = getHealthMessage(bmi);
    
  };
  
  form.addEventListener('submit', onSubmit, false);
	
})();