fix(normalize): remove decimal point normalization

Author: sudkumar

README.md

@@ -22,6 +22,9 @@ You can use basic operations (e.g. +, -, \*, /, %, ^ etc.) in you expressions.
 - 175 + 175 \* 18% + 40 = 246.5
 - 10 + (100 - 100 \* 18%) \* 5 + 40 / 20 = 422
 
+> _NOTE_: Floating points must be handled carefully. Use `Number(<number>).toFixed(<digits>)` to fix the digits after
+> decimal point.
+
 ## Api
 
 ### evalExpr

src/index.test.ts

@@ -17,7 +17,7 @@ describe("Evaluate Numerical Expressions", () => {
   it("Grouping via parenthesis", () => {
     expect(evalNumExpr("1 +(1 +2) * 4/2")).toBe(7);
     expect(evalNumExpr("3 * ((4 + 2) / 2)")).toEqual(9);
-    expect(evalNumExpr("3 + 4 x 2 / ( 1 - 5 ) ^ 2 ^ 3")).toEqual(3);
+    expect(evalNumExpr("3 + 128 x 2 / ( 1 - 3 ) ^ 2 ^ 2")).toEqual(19);
   });
 
   it("Throws expressions for invalid inputs", () => {

src/index.ts

@@ -1,10 +1,7 @@
 /**
  * https://en.wikipedia.org/wiki/Shunting-yard_algorithm
  */
-export default function evalNumExpr(
-  amount: string,
-  digitsAfterDecimal: number = 2
-): number {
+export default function evalNumExpr(amount: string): number {
   // operators with Precedence and Associativity
   const operators = [
     new Operator("-", 2),
@@ -90,22 +87,9 @@ export default function evalNumExpr(
     // stack has more than one number and we are out of operators
     throw new Error("Missing operators.");
   }
-  return normalizeNumber(values.pop(), digitsAfterDecimal);
+  return values.pop();
 }
 
-function normalizeNumber(
-  n: number,
-  digitsAfterDecimal: number | undefined = 2
-): number {
-  let str = n.toString();
-  if (digitsAfterDecimal !== undefined) {
-    str = Number(str).toFixed(digitsAfterDecimal).toString();
-  }
-  if (parseInt(str) === parseFloat(str)) {
-    str = parseInt(str).toString();
-  }
-  return Number(str);
-}
 type OperatorFns = "-" | "+" | "/" | "*" | "^";
 
 class Operator {

types/index.d.ts

@@ -1,4 +1,9 @@
-export default function evalNumExpr(
-  expression: string,
-  digitsAfterDecimal?: number
-): number;
+/**
+ * Evaluate numeric mathematical expression
+ * @param string expression - The expression to evaluate ("24 + 65 * 3 - 48")
+ * @return number - The evaluated value.
+ *
+ * NOTE: When passing floating points, please handle the digits after decimal point
+ * e.g. 2 - 1.1 leads to 0.8999999999999999 intead of .9
+ */
+export default function evalNumExpr(expression: string): number;