Implements a consecutive operator checker

__tests__/script.test.js

@@ -0,0 +1,26 @@
+const { describe, test, expect } = require("@jest/globals");
+const { isNullOrEmptyInput, countOperators, checkConsecutive } = require("../scripts/validator");
+
+describe("check input", () => {
+	test("check for empty or null input", () => {
+		const input = "";
+
+		expect(isNullOrEmptyInput(input)).toBe(true);
+	});
+
+	test("check number of math operators", () => {
+		const inputs = ["50+10+20"];
+
+		expect(countOperators(inputs[0])).toBe(2);
+	});
+
+	test("check consecutive math operators", () => {
+		const inputs = ["--50", "50--", "50***", "//50", "1+50"];
+
+		expect(checkConsecutive(inputs[0])).toBe(2);
+		expect(checkConsecutive(inputs[1])).toBe(2);
+		expect(checkConsecutive(inputs[2])).toBe(3);
+		expect(checkConsecutive(inputs[3])).toBe(2);
+		expect(checkConsecutive(inputs[4])).toBe(1);
+	});
+});

package.json

@@ -0,0 +1,16 @@
+{
+  "name": "Calculator",
+  "version": "1.0.0",
+  "description": "Calculator app",
+  "main": "index.js",
+  "repository": "https://github.com/zxcodes/Calculator.git",
+  "author": "Mohammed Farmaan <farmaanghouse6@gmail.com>",
+  "license": "MIT",
+  "dependencies": {},
+  "devDependencies": {
+    "jest": "^29.7.0"
+  },
+  "scripts": {
+    "test": "jest tests"
+  }
+}

scripts/script.js

@@ -7,102 +7,150 @@ const res = document.getElementById("result");
 const toast = document.getElementById("toast");
 
 function calculate(value) {
-  const calculatedValue = eval(value || null);
-  if (isNaN(calculatedValue)) {
-    res.value = "Can't divide 0 with 0";
-    setTimeout(() => {
-      res.value = "";
-    }, 1300);
-  } else {
-    res.value = calculatedValue;
-  }
+	if (checkConsecutive(value) > 1) {
+		alert("invalid expression");
+		return;
+	}
+
+	const calculatedValue = eval(value || null);
+	if (isNaN(calculatedValue)) {
+		res.value = "Can't divide 0 with 0";
+		setTimeout(() => {
+			res.value = "";
+		}, 1300);
+	} else {
+		res.value = calculatedValue;
+	}
 }
 
 // Swaps the stylesheet to achieve dark mode.
 function changeTheme() {
-  const theme = document.getElementById("theme");
-  setTimeout(() => {
-    toast.innerHTML = "Calculator";
-  }, 1500);
-  if (theme.getAttribute("href") === lightTheme) {
-    theme.setAttribute("href", darkTheme);
-    themeIcon.setAttribute("src", sunIcon);
-    toast.innerHTML = "Dark Mode 🌙";
-  } else {
-    theme.setAttribute("href", lightTheme);
-    themeIcon.setAttribute("src", moonIcon);
-    toast.innerHTML = "Light Mode ☀️";
-  }
+	const theme = document.getElementById("theme");
+	setTimeout(() => {
+		toast.innerHTML = "Calculator";
+	}, 1500);
+	if (theme.getAttribute("href") === lightTheme) {
+		theme.setAttribute("href", darkTheme);
+		themeIcon.setAttribute("src", sunIcon);
+		toast.innerHTML = "Dark Mode 🌙";
+	} else {
+		theme.setAttribute("href", lightTheme);
+		themeIcon.setAttribute("src", moonIcon);
+		toast.innerHTML = "Light Mode ☀️";
+	}
 }
 
 // Displays entered value on screen.
 function liveScreen(enteredValue) {
-  if (!res.value) {
-    res.value = "";
-  }
-  res.value += enteredValue;
+	if (!res.value) {
+		res.value = "";
+	}
+	res.value += enteredValue;
 }
 
 //adding event handler on the document to handle keyboard inputs
 document.addEventListener("keydown", keyboardInputHandler);
 
 //function to handle keyboard inputs
 function keyboardInputHandler(e) {
-  // to fix the default behavior of browser,
-  // enter and backspace were causing undesired behavior when some key was already in focus.
-  e.preventDefault();
-  //grabbing the liveScreen
-
-  //numbers
-  if (e.key === "0") {
-    res.value += "0";
-  } else if (e.key === "1") {
-    res.value += "1";
-  } else if (e.key === "2") {
-    res.value += "2";
-  } else if (e.key === "3") {
-    res.value += "3";
-  } else if (e.key === "4") {
-    res.value += "4";
-  } else if (e.key === "5") {
-    res.value += "5";
-  } else if (e.key === "6") {
-    res.value += "6";
-  } else if (e.key === "7") {
-    res.value += "7";
-  } else if (e.key === "7") {
-    res.value += "7";
-  } else if (e.key === "8") {
-    res.value += "8";
-  } else if (e.key === "9") {
-    res.value += "9";
-  }
-
-  //operators
-  if (e.key === "+") {
-    res.value += "+";
-  } else if (e.key === "-") {
-    res.value += "-";
-  } else if (e.key === "*") {
-    res.value += "*";
-  } else if (e.key === "/") {
-    res.value += "/";
-  }
-
-  //decimal key
-  if (e.key === ".") {
-    res.value += ".";
-  }
-
-  //press enter to see result
-  if (e.key === "Enter") {
-    calculate(result.value);
-  }
-
-  //backspace for removing the last input
-  if (e.key === "Backspace") {
-    const resultInput = res.value;
-    //remove the last element in the string
-    res.value = resultInput.substring(0, res.value.length - 1);
-  }
+	// to fix the default behavior of browser,
+	// enter and backspace were causing undesired behavior when some key was already in focus.
+	e.preventDefault();
+	//grabbing the liveScreen
+
+	//numbers
+	if (e.key === "0") {
+		res.value += "0";
+	} else if (e.key === "1") {
+		res.value += "1";
+	} else if (e.key === "2") {
+		res.value += "2";
+	} else if (e.key === "3") {
+		res.value += "3";
+	} else if (e.key === "4") {
+		res.value += "4";
+	} else if (e.key === "5") {
+		res.value += "5";
+	} else if (e.key === "6") {
+		res.value += "6";
+	} else if (e.key === "7") {
+		res.value += "7";
+	} else if (e.key === "7") {
+		res.value += "7";
+	} else if (e.key === "8") {
+		res.value += "8";
+	} else if (e.key === "9") {
+		res.value += "9";
+	}
+
+	//operators
+	if (e.key === "+") {
+		res.value += "+";
+	} else if (e.key === "-") {
+		res.value += "-";
+	} else if (e.key === "*") {
+		res.value += "*";
+	} else if (e.key === "/") {
+		res.value += "/";
+	}
+
+	//decimal key
+	if (e.key === ".") {
+		res.value += ".";
+	}
+
+	//press enter to see result
+	if (e.key === "Enter") {
+		calculate(result.value);
+	}
+
+	//backspace for removing the last input
+	if (e.key === "Backspace") {
+		const resultInput = res.value;
+		//remove the last element in the string
+		res.value = resultInput.substring(0, res.value.length - 1);
+	}
+}
+
+function isNullOrEmptyInput(input) {
+	if (input.length == 0 || input == null) {
+		return true;
+	}
+
+	return false;
+}
+
+function countOperators(input) {
+	let count = 0;
+	let operator = "+";
+
+	for (let i = 0; i < input.length; i++) {
+		if (input[i] == operator) {
+			count++;
+		}
+	}
+
+	return count;
+}
+
+function checkConsecutive(input) {
+	let operators = ["+", "-", "*", "/"];
+	let count = 0;
+	let countCurrent = 0;
+	let counts = [];
+
+	operators.forEach((element) => {
+		for (let i = 0; i < input.length; i++) {
+			if (input[i] === element) {
+				countCurrent++;
+				count = Math.max(count, countCurrent);
+			} else {
+				countCurrent = 0;
+			}
+		}
+
+		counts.push(count);
+	});
+
+	return Math.max(...counts);
 }

scripts/validator.js

@@ -0,0 +1,44 @@
+function isNullOrEmptyInput(input) {
+	if (input.length == 0 || input == null) {
+		return true;
+	}
+
+	return false;
+}
+
+function countOperators(input) {
+	let count = 0;
+	let operator = "+";
+
+	for (let i = 0; i < input.length; i++) {
+		if (input[i] == operator) {
+			count++;
+		}
+	}
+
+	return count;
+}
+
+function checkConsecutive(input) {
+	let operators = ["+", "-", "*", "/"];
+	let count = 0;
+	let countCurrent = 0;
+	let counts = [];
+
+	operators.forEach((element) => {
+		for (let i = 0; i < input.length; i++) {
+			if (input[i] === element) {
+				countCurrent++;
+				count = Math.max(count, countCurrent);
+			} else {
+				countCurrent = 0;
+			}
+		}
+
+		counts.push(count);
+	});
+
+	return Math.max(...counts);
+}
+
+module.exports = { isNullOrEmptyInput, countOperators, checkConsecutive };