code-boxx/0-JS-BMI.MD

## 0-JS-BMI.MD

      
    Raw
  

              0-JS-BMI.MD
            
          
    JAVASCRIPT BMI CALCULATOR

https://code-boxx.com/simple-javascript-bmi-calculator/
LICENSE

Copyright by Code Boxx
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

  
## 1-bmi.css
/* (X) DOES NOT MATTER, COSMETICS */
* {
  font-family: Arial, Helvetica, sans-serif;
  box-sizing: border-box;
}
#bmi-form input[type=text], #bmi-form input[type=number] {
  border: 1px solid #cfcfcf;
  padding: 5px;
}
#bmi-form input[type=number] { width: 100%; }
#bmi-form input[type=submit] {
  padding: 10px;
  border: 0;
  color: #fff;
  background: #3e5eb7;
  cursor: pointer;
}
#bmi-form {
  border: 1px solid #eee;
  background: #f2f2f2;
  padding: 20px;
  max-width: 400px;
}
#bmi-form .bmi-label {
  color: #00a8c3;
  font-weight: 700;
  margin: 10px 0;
}
#bmi-form .bmi-row {
  margin-bottom: 20px;
}

## 1-bmi.html
<!DOCTYPE html>
<html>
  <head>
    <title>Simple BMI Calculator</title>
    <link rel="stylesheet" href="1-bmi.css">
    <script src="2-bmi.js"></script>
  </head>
  <body>
    <form id="bmi-form" onsubmit="return calcBMI();">
      <div class="bmi-label">System:</div>
      <div class="bmi-row">
        <label>
          <input type="radio" id="bmi-metric" name="bmi-measure" onchange="measureBMI()" checked> Metric
        </label>
        <label>
          <input type="radio" id="bmi-imperial" name="bmi-measure" onchange="measureBMI()"> Imperial
        </label>
      </div>

      <div class="bmi-label">
        Weight (<span id="bmi-weight-unit">KG</span>):
      </div>
      <div class="bmi-row">
        <input id="bmi-weight" type="number" min="1" max="635" required>
      </div>

      <div class="bmi-label">Height (<span id="bmi-height-unit">CM</span>):</div>
      <div class="bmi-row">
        <input id="bmi-height" type="number" min="54" max="272" required>
      </div>

      <input type="submit" value="Calculate BMI">
      <span id="bmi-results"></span>
    </form>
  </body>
</html>

## 2-bmi.js
// (A) CHANGE BMI MEASURING SYSTEM
function measureBMI () {
  // (A1) GET HTML ELEMENTS
  let unit = document.getElementById("bmi-metric").checked,
      weight = document.getElementById("bmi-weight"),
      weightu = document.getElementById("bmi-weight-unit"),
      height = document.getElementById("bmi-height"),
      heightu = document.getElementById("bmi-height-unit");

  // (A2) UPDATE HTML FORM FIELDS
  // TRUE = METRIC, FALSE = IMPERIAL
  if (unit) {
    weightu.innerHTML = "KG";
    weight.min = 1; weight.max = 635;
    heightu.innerHTML = "CM";
    height.min = 54; height.max = 272;
  } else {
    weightu.innerHTML = "LBS";
    weight.min = 2; weight.max = 1400;
    heightu.innerHTML = "IN";
    height.min = 21; height.max = 107;
  }
}

// (B) CALCULATE BMI
function calcBMI () {
  // (B1) GET HTML ELEMENTS
  let bmi = null,
      unit = document.getElementById("bmi-metric").checked,
      weight = parseInt(document.getElementById("bmi-weight").value),
      height = parseInt(document.getElementById("bmi-height").value),
      results = document.getElementById("bmi-results");

  // (B2) CALCULATE BMI
  // METRIC BMI = MASS (KG) / HEIGHT (M) SQUARE
  if (unit) {
    height = height / 100;
    bmi = weight / (height * height);
  }
  // IMPERIAL BMI = 703 X MASS (LBS) / HEIGHT (IN) SQUARE
  else {
    bmi = 703 * (weight / (height * height));
  }
  // ROUND OFF - 2 DECIMAL PLACES
  bmi = Math.round(bmi * 100) / 100;

  // (B3) SHOW RESULTS
  if (bmi < 18.5) {
    results.innerHTML = bmi + " - Underweight";
  } else if (bmi < 25) {
    results.innerHTML = bmi + " - Normal weight";
  } else if (bmi < 30) {
    results.innerHTML = bmi + " - Pre-obesity";
  } else if (bmi < 35) {
    results.innerHTML = bmi + " - Obesity class I";
  } else if (bmi < 40) {
    results.innerHTML = bmi + " - Obesity class II";
  } else {
    results.innerHTML = bmi + " - Obesity class III";
  }
  return false;
}
	/* (X) DOES NOT MATTER, COSMETICS */
	* {
	font-family: Arial, Helvetica, sans-serif;
	box-sizing: border-box;
	}
	#bmi-form input[type=text], #bmi-form input[type=number] {
	border: 1px solid #cfcfcf;
	padding: 5px;
	}
	#bmi-form input[type=number] { width: 100%; }
	#bmi-form input[type=submit] {
	padding: 10px;
	border: 0;
	color: #fff;
	background: #3e5eb7;
	cursor: pointer;
	}
	#bmi-form {
	border: 1px solid #eee;
	background: #f2f2f2;
	padding: 20px;
	max-width: 400px;
	}
	#bmi-form .bmi-label {
	color: #00a8c3;
	font-weight: 700;
	margin: 10px 0;
	}
	#bmi-form .bmi-row {
	margin-bottom: 20px;
	}
	<!DOCTYPE html>
	<html>
	<head>
	<title>Simple BMI Calculator</title>
	<link rel="stylesheet" href="1-bmi.css">
	<script src="2-bmi.js"></script>
	</head>
	<body>
	<form id="bmi-form" onsubmit="return calcBMI();">
	<div class="bmi-label">System:</div>
	<div class="bmi-row">
	<label>
	<input type="radio" id="bmi-metric" name="bmi-measure" onchange="measureBMI()" checked> Metric
	</label>
	<label>
	<input type="radio" id="bmi-imperial" name="bmi-measure" onchange="measureBMI()"> Imperial
	</label>
	</div>

	<div class="bmi-label">
	Weight (<span id="bmi-weight-unit">KG</span>):
	</div>
	<div class="bmi-row">
	<input id="bmi-weight" type="number" min="1" max="635" required>
	</div>

	<div class="bmi-label">Height (<span id="bmi-height-unit">CM</span>):</div>
	<div class="bmi-row">
	<input id="bmi-height" type="number" min="54" max="272" required>
	</div>

	<input type="submit" value="Calculate BMI">
	<span id="bmi-results"></span>
	</form>
	</body>
	</html>
	// (A) CHANGE BMI MEASURING SYSTEM
	function measureBMI () {
	// (A1) GET HTML ELEMENTS
	let unit = document.getElementById("bmi-metric").checked,
	weight = document.getElementById("bmi-weight"),
	weightu = document.getElementById("bmi-weight-unit"),
	height = document.getElementById("bmi-height"),
	heightu = document.getElementById("bmi-height-unit");

	// (A2) UPDATE HTML FORM FIELDS
	// TRUE = METRIC, FALSE = IMPERIAL
	if (unit) {
	weightu.innerHTML = "KG";
	weight.min = 1; weight.max = 635;
	heightu.innerHTML = "CM";
	height.min = 54; height.max = 272;
	} else {
	weightu.innerHTML = "LBS";
	weight.min = 2; weight.max = 1400;
	heightu.innerHTML = "IN";
	height.min = 21; height.max = 107;
	}
	}

	// (B) CALCULATE BMI
	function calcBMI () {
	// (B1) GET HTML ELEMENTS
	let bmi = null,
	unit = document.getElementById("bmi-metric").checked,
	weight = parseInt(document.getElementById("bmi-weight").value),
	height = parseInt(document.getElementById("bmi-height").value),
	results = document.getElementById("bmi-results");

	// (B2) CALCULATE BMI
	// METRIC BMI = MASS (KG) / HEIGHT (M) SQUARE
	if (unit) {
	height = height / 100;
	bmi = weight / (height * height);
	}
	// IMPERIAL BMI = 703 X MASS (LBS) / HEIGHT (IN) SQUARE
	else {
	bmi = 703 * (weight / (height * height));
	}
	// ROUND OFF - 2 DECIMAL PLACES
	bmi = Math.round(bmi * 100) / 100;

	// (B3) SHOW RESULTS
	if (bmi < 18.5) {
	results.innerHTML = bmi + " - Underweight";
	} else if (bmi < 25) {
	results.innerHTML = bmi + " - Normal weight";
	} else if (bmi < 30) {
	results.innerHTML = bmi + " - Pre-obesity";
	} else if (bmi < 35) {
	results.innerHTML = bmi + " - Obesity class I";
	} else if (bmi < 40) {
	results.innerHTML = bmi + " - Obesity class II";
	} else {
	results.innerHTML = bmi + " - Obesity class III";
	}
	return false;
	}