Executing Postfix expression implementation using Javascript

PostFix.js

/**
 * 
 * Postfix implementation using StackList: 
 * Code for stacklist: https://gist.github.com/dineshrajpurohit/0bb67d29a039f85f2f10
 * 
 * Dinesh
 * 
 * PostFix Expression parsing and getting the result
 * 
 *  e.g: 42+351-*+ ==> 18
 *  
 *  Postfix parsing is implemented using Stacks
 *  Algorithm:
 *   - Whenever Integer come in from an expression add it to stack
 *   - Whenever and operator comes in from the expression add remove the top
 *     2 Integer from the stack and operate on them using the operator
 *   - Repeat this until the entire expression is done
 *   - Print the stack item
 *  
 **/
EX.PostFix = function(expression){
		this.expression = expression;
		var numStack = new EX.LinkedStack();
		
		for(var i=0; i<expression.length; i++){
			c = expression.charAt(i);
			if(!isNaN(parseInt(c))){
				numStack.pushToStack(parseInt(c));
			}else if(c === '+' || c === '-' || c==='*' || c==='/' || c==='^'){
				this.constructor.operate(numStack, c);
			}
		}

	this.getResult = function(){
		return  numStack.stackTop().
		
	}	
}

// Static method to add the Integer based on the opration
EX.PostFix.operate = function(obj, operator){
	var operand2 = obj.popFromStack().item;
	var operand1 = obj.popFromStack().item;
	switch(operator){
	case "+":
		obj.pushToStack(operand1+operand2);
		break;
	case "-":
		obj.pushToStack(operand1-operand2);
		break;
	case "*":
		obj.pushToStack(operand1*operand2);
		break;
	case "/":
		obj.pushToStack(parseInt(operand1/operand2));
		break;
	case "^":
		obj.pushToStack(Math.pow(operand1, operand2));
		break;
	}
}


console.log(" POSTFIX 42+351-");
var pfix = new EX.PostFix("42+351-*+"); 
console.log("Result for Expression: " + pfix.getResult());

/**
 * OUT PUT 
 *
 *  POSTFIX 42+351- expressions_parsing.js:167
 * Result for Expression: 18 
 * 
 */