think49/calculation-sample.html

## calculation-sample.html
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8" />
<title>calculation-sample.js</title>
<script>
/**
 * calculation-sample.js
 * evaluate calculation formula.
 *
 * @version 0.1.1
 * @author think49
 * @url https://gist.github.com/think49/3c484937a84c91cd5c51f5788c7c34c7
 * @license http://www.opensource.org/licenses/mit-license.php (The MIT License)
 */
'use strict';
var Calculation = (function (String, pow, max) {
  'use strict';

  function getDecimalPartLength (numberString) {
    var result = /\.\d+$/.exec(numberString);

    return result ? result[0].length - 1 : 0;
  }

  function calcDyadicOperator (matched, number1, operator, number2) {
    var decimalPart = /\.\d+$/, powerNumber1, powerNumber2, result;

    switch (operator) {
      case '+':
        powerNumber1 = pow(10, max(getDecimalPartLength(number1), getDecimalPartLength(number2)));
        result = (powerNumber1 * number1 + powerNumber1 * number2) / powerNumber1;
      break;
    case '-':
        powerNumber1 = pow(10, max(getDecimalPartLength(number1), getDecimalPartLength(number2)));
        result = (powerNumber1 * number1 - powerNumber1 * number2) / powerNumber1;
      break;
    case '*':
        powerNumber1 = pow(10, getDecimalPartLength(number1));
        powerNumber2 = pow(10, getDecimalPartLength(number2));
        result = (number1 * powerNumber1) * (number2 * powerNumber2) / (powerNumber1 * powerNumber2);
      break;
    case '/':
        powerNumber1 = pow(10, max(getDecimalPartLength(number1), getDecimalPartLength(number2)));
        result = (number1 * powerNumber1) / (number2 * powerNumber1);
      break;
    default:
      console.warn('expression: ' + number1 + operator + number2);
      throw new Error(operator + ' is not a operator');
    }

    // console.log(String(number1) + operator + number2 + '=' + result);
    return result;
  }

  return {
    eval: function _eval (expression) {
      var multiplyOrDivide = /(-?(?:\d+(?:\.\d+)?|\.\d+))([*/])(-?(?:\d+(?:\.\d+)?|\.\d+))/g,
          addOrSubtract = /(-?(?:\d+(?:\.\d+)?|\.\d+))([+-])(-?(?:\d+(?:\.\d+)?|\.\d+))/g;

      while (multiplyOrDivide.test(expression)) {
        expression = expression.replace(multiplyOrDivide, calcDyadicOperator);
      }

      while (addOrSubtract.test(expression)) {
        expression = expression.replace(addOrSubtract, calcDyadicOperator);
      }

      return +expression;
    },
    checkSyntax: function checkSyntax (expression) {
      var errors = [], illegalString;

      expression = String(expression).replace(/\s+/g, '');

      if (illegalString = /^[+-]?(?:\.[^\d]|[^\d.+-])/.exec(expression)) {
        errors.push(new SyntaxError('An expression starts with an unexpected token: ' + illegalString[0]));
      }

      if (illegalString = /[^\d]$/.exec(expression)) {
        errors.push(new SyntaxError('An expression ends with an unexpected token: ' + illegalString[0]));
      }

      if (illegalString = /\d*(?:\.\d*){2,}/.exec(expression)) {
        errors.push(new SyntaxError('Illegal number: ' + illegalString[0]));
      }

      return errors;
    }
  };
}(String, Math.pow, Math.max));
</script>
</head>
<body>
<ul>
  <li><a href="https://teratail.com/questions/54897#r88052">JavaScript - エラーメッセージをまとめて出力する為の最適解は？(54897)｜teratail</a></li>
</ul>
<script>
'use strict';
console.log(Calculation.eval('/1.1.1*')); // NaN
console.log(Calculation.checkSyntax('/1.1.1*'));  // [new SyntaxError('An expression starts with an unexpected token: /'), new SyntaxError('An expression ends with an unexpected token: *'), new SyntaxError('Illegal number: 1.1.1')]
</script>
</body>
</html>
	<!DOCTYPE html>
	<html>
	<head>
	<meta charset="UTF-8" />
	<title>calculation-sample.js</title>
	<script>
	/**
	* calculation-sample.js
	* evaluate calculation formula.
	*
	* @version 0.1.1
	* @author think49
	* @url https://gist.github.com/think49/3c484937a84c91cd5c51f5788c7c34c7
	* @license http://www.opensource.org/licenses/mit-license.php (The MIT License)
	*/
	'use strict';
	var Calculation = (function (String, pow, max) {
	'use strict';

	function getDecimalPartLength (numberString) {
	var result = /\.\d+$/.exec(numberString);

	return result ? result[0].length - 1 : 0;
	}

	function calcDyadicOperator (matched, number1, operator, number2) {
	var decimalPart = /\.\d+$/, powerNumber1, powerNumber2, result;

	switch (operator) {
	case '+':
	powerNumber1 = pow(10, max(getDecimalPartLength(number1), getDecimalPartLength(number2)));
	result = (powerNumber1 * number1 + powerNumber1 * number2) / powerNumber1;
	break;
	case '-':
	powerNumber1 = pow(10, max(getDecimalPartLength(number1), getDecimalPartLength(number2)));
	result = (powerNumber1 * number1 - powerNumber1 * number2) / powerNumber1;
	break;
	case '*':
	powerNumber1 = pow(10, getDecimalPartLength(number1));
	powerNumber2 = pow(10, getDecimalPartLength(number2));
	result = (number1 * powerNumber1) * (number2 * powerNumber2) / (powerNumber1 * powerNumber2);
	break;
	case '/':
	powerNumber1 = pow(10, max(getDecimalPartLength(number1), getDecimalPartLength(number2)));
	result = (number1 * powerNumber1) / (number2 * powerNumber1);
	break;
	default:
	console.warn('expression: ' + number1 + operator + number2);
	throw new Error(operator + ' is not a operator');
	}

	// console.log(String(number1) + operator + number2 + '=' + result);
	return result;
	}

	return {
	eval: function _eval (expression) {
	var multiplyOrDivide = /(-?(?:\d+(?:\.\d+)?\|\.\d+))([*/])(-?(?:\d+(?:\.\d+)?\|\.\d+))/g,
	addOrSubtract = /(-?(?:\d+(?:\.\d+)?\|\.\d+))([+-])(-?(?:\d+(?:\.\d+)?\|\.\d+))/g;

	while (multiplyOrDivide.test(expression)) {
	expression = expression.replace(multiplyOrDivide, calcDyadicOperator);
	}

	while (addOrSubtract.test(expression)) {
	expression = expression.replace(addOrSubtract, calcDyadicOperator);
	}

	return +expression;
	},
	checkSyntax: function checkSyntax (expression) {
	var errors = [], illegalString;

	expression = String(expression).replace(/\s+/g, '');

	if (illegalString = /^[+-]?(?:\.[^\d]\|[^\d.+-])/.exec(expression)) {
	errors.push(new SyntaxError('An expression starts with an unexpected token: ' + illegalString[0]));
	}

	if (illegalString = /[^\d]$/.exec(expression)) {
	errors.push(new SyntaxError('An expression ends with an unexpected token: ' + illegalString[0]));
	}

	if (illegalString = /\d(?:\.\d){2,}/.exec(expression)) {
	errors.push(new SyntaxError('Illegal number: ' + illegalString[0]));
	}

	return errors;
	}
	};
	}(String, Math.pow, Math.max));
	</script>
	</head>
	<body>
	<ul>
	<li><a href="https://teratail.com/questions/54897#r88052">JavaScript - エラーメッセージをまとめて出力する為の最適解は？(54897)｜teratail</a></li>
	</ul>
	<script>
	'use strict';
	console.log(Calculation.eval('/1.1.1*')); // NaN
	console.log(Calculation.checkSyntax('/1.1.1')); // [new SyntaxError('An expression starts with an unexpected token: /'), new SyntaxError('An expression ends with an unexpected token: '), new SyntaxError('Illegal number: 1.1.1')]
	</script>
	</body>
	</html>