Websparks Nodejs Test

questions.md

Q1:

• This calculator takes values that could be written in a browsers route path as a single string. It then returns the result as a number (or an error message).

• Route paths use the '/' symbol so this can't be in our calculator. Instead we are using the '$' symbol as our divide operator.

• You will be passed a string of any length containing numbers and operators:

  • '+' = add
  • '-' = subtract
  • '*' = multiply
  • '$' = divide

• Your task is to break the string down and calculate the expression using this order of operations. (division => multiplication => subtraction => addition)

• If you are given an invalid input (i.e. any character except .0123456789+-*$) you should return the error message:'400: Bad request'

• Remember:

  • Operations are infinite
  • Order of operations is imperative
  • No eval or equivalent functions

• Examples:

  calculate('1+1') => '2'
  calculate('10$2') => '5'
  calculate('1.5\*3') => '4.5'
  calculate('5+5+5+5') => '20'
  calculate('1000$2.5$5+5-5+6$6') =>'81'
  calculate('10-9p') => '400: Bad request'

---

Q2:

• Move the first letter of each word to the end of it, then add "ay" to the end of the word. Leave punctuation marks untouched.

• Examples:

pigIt('Pig latin is cool'); // igPay atinlay siay oolcay
pigIt('Hello world !'); // elloHay orldway !

function calculate(str) {
	if (!str.match(/^[0-9.+\-*$]+$/)) return '400: Bad request';

	let expression = str.split(/([+\-*$])/);
	expression = expression.map((val) => val.replace('$', '/'));

	while (expression.length > 1) {
		let divideIndex = expression.indexOf('/');
		if (divideIndex > -1) {
			let divideCalc =
				expression[divideIndex - 1] / expression[divideIndex + 1];
			expression.splice(divideIndex - 1, 3, divideCalc);
		} else {
			let multiplyIndex = expression.indexOf('*');
			if (multiplyIndex > -1) {
				let multiplyCalc =
					expression[multiplyIndex - 1] * expression[multiplyIndex + 1];
				expression.splice(multiplyIndex - 1, 3, multiplyCalc);
			} else {
				let subtractIndex = expression.indexOf('-');
				if (subtractIndex > -1) {
					let subtractCalc =
						expression[subtractIndex - 1] - expression[subtractIndex + 1];
					expression.splice(subtractIndex - 1, 3, subtractCalc);
				} else {
					let addIndex = expression.indexOf('+');
					if (addIndex > -1) {
						let addCalc =
							parseFloat(expression[addIndex - 1]) +
							parseFloat(expression[addIndex + 1]);
						expression.splice(addIndex - 1, 3, addCalc);
					}
				}
			}
		}
	}
  
	return expression[0];
}

function pigIt(str) {
	let result = '';

	str.split(' ').forEach((word) => {
		if (word.match(/^[a-zA-Z]+$/)) {
			result += word.substring(1, word.length) + word.substring(0, 1) + 'ay ';
		} else {
			result += word + ' ';
		}
	});

	return result.trim();
}