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simple javascript calculator
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| var PlainCalculator = (function() { | |
| const ExpressionSide = { | |
| LEFT: 0, | |
| RIGHT:2 | |
| }; | |
| const ExpressionType = { | |
| NUMBER: 0, | |
| OPERAND: 1, | |
| } | |
| function ExpressionContent(val, type) { | |
| this.val = val; | |
| this.type = type; | |
| } | |
| function ExpressionMath(left,middle,right, next) { | |
| this.left = left; | |
| this.middle = middle; | |
| this.right = right; | |
| this.next = next; | |
| } | |
| function BuildTree(mathExpression) | |
| { | |
| var mathExpArray = mathExpression.split(''); | |
| var expContent = new ExpressionContent(null, null); | |
| for(var i = 0; i < mathExpArray.length; i++) | |
| { | |
| var val = mathExpArray[i]; | |
| var expSide = ExpressionSide.LEFT; | |
| if(expType === ExpressionSide.LEFT && isNumber(val)){ | |
| expContent.val = val; | |
| expContent. | |
| } else if(isNull(operator) && isOperator(val)) | |
| { | |
| } else if(expType === ExpressionSide.RIGHT && isNumber(val)){ | |
| } else { | |
| throw new Exception("ERROR NOT ABLE TO PROCESS"); | |
| } | |
| } | |
| } | |
| function ProcessExpression(mathExpression) { | |
| var total = 0; | |
| var mathExpArray = mathExpression.split(''); | |
| var left = '', operator = null, right =''; | |
| var expType = ExpressionSide.LEFT; | |
| for(var i = 0; i < mathExpArray.length; i++) | |
| { | |
| var val = mathExpArray[i]; | |
| if(expType === ExpressionSide.LEFT && isNumber(val)){ | |
| left += val; | |
| } else if(isNull(operator) && isOperator(val)) | |
| { | |
| operator = val; | |
| expType = ExpressionSide.RIGHT; | |
| } else if(expType === ExpressionSide.RIGHT && isNumber(val)){ | |
| right += val; | |
| } else { | |
| throw new Exception("ERROR NOT ABLE TO PROCESS"); | |
| } | |
| // left OPERAND right | |
| /* | |
| if(isNumber(left) === true && isNumber(right) === true && isOperator(operator) === true) | |
| { | |
| total = doMath(left, operator, right); | |
| expType = ExpressionSide.LEFT; | |
| left = ''; | |
| operator = null; | |
| right = ''; | |
| } | |
| */ | |
| } | |
| return left; | |
| } | |
| function isNumber(val){ | |
| return !isNull(val) && val !== "" && !isNaN(val); | |
| } | |
| function isNull(val){ | |
| return val === null; | |
| } | |
| function isOperator(op){ | |
| var is = false; | |
| switch(op){ | |
| case '+': | |
| case '-': | |
| case '/': | |
| is = true; | |
| break; | |
| } | |
| return is; | |
| } | |
| function doMath(l, op, r){ | |
| console.log(l, op, r); | |
| if(op === '+'){ | |
| return Number(l) + Number(r); | |
| } | |
| if(op === '-') { | |
| return Number(l) - Number(r); | |
| } | |
| if(op === '/') { | |
| return Number(l) / Number(r); | |
| } | |
| throw new Exception(' no operator to apply'); | |
| } | |
| return { | |
| 'buildTree': buildTree, | |
| 'evaluate': ProcessExpression | |
| } | |
| })(); | |
| /*EXAMPLE */ | |
| PlainCalculator.evaluate('3+3'); //->9 |
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