javascript on your machine

index.js

@@ -4,7 +4,36 @@
  * Depending on the operation, either add up all of the numbers or subtract all of the numbers, from left to right.
  * @returns {number} The result of either adding all numbers or subtracting all numbers, depending on the arguments added to the command line.
  */
-function calculator() {}
+function calculator() {
+    console.log(process.argv)
+    let operator = process.argv[2]
+    // checking for no operation
+    if (!operator){
+        return "No operation provided..."
+    } 
+    // checking for numbers
+    if (process.argv[3] === undefined){
+        return "No numbers provided..."
+    }
+    // check for other operators that are not plus or minus
+    if (!(operator.includes("plus") || operator.includes('minus'))) {
+        return `Invalid operation: ${operator}`
+    }
+    // for loop: initialize, condition, change
+    let sum = Number(process.argv[3])
+    for (let i = 4; i < process.argv.length; i++) {
+         // plus operation
+    if (operator === "plus") {
+        sum += Number(process.argv[i])
+    } else if (operator === "minus") {
+        sum -= process.argv[i]
+    }   
+    }// end of for loop
+
+        return sum
+    }// end of function
+
+
 
 // Don't change anything below this line.
 module.exports = calculator;