JavaScript-Courses/constructor-new-lab3.html at master · AndreyKrotkikh/JavaScript-Courses · GitHub

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<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
</head>
<body>

	<script>

		function Calculator() {

			var methods = {
				"+" : function(a,b) {
					return a + b;
				},

				"-" : function(a,b) {
					return a + b;
				}
			}

			this.calculate = function(string) {

				var splStr = string.split(' ');

				return methods[splStr[1]](+splStr[0],+splStr[2]);
		  	};

		  	this.addMethod = function(string,func) {

				methods[string] = func;
		  	};

		}

		var calc = new Calculator;

		alert( calc.calculate("3 + 7") ); // 10

		var powerCalc = new Calculator;

		powerCalc.addMethod("*", function(a, b) {
		  return a * b;
		});

		powerCalc.addMethod("/", function(a, b) {
		  return a / b;
		});

		powerCalc.addMethod("**", function(a, b) {
		  return Math.pow(a, b);
		});

		var result = powerCalc.calculate("2 ** 3");
		alert( result ); // 8


	</script>

</body>
</html>