add guided calculator class

calculator.js

@@ -0,0 +1,101 @@
+class Calculator {
+	result = 0;
+	expression = [];
+
+	#config;
+
+	/*
+	Perform a calculation.
+	*/
+	calculate(parameters) {
+		this.input = this.expression.join(``);
+
+		// Evaluate. 
+		try {
+			this.result = eval(this.input);
+			delete this.input;
+
+			if (this.result === Infinity || this.result === NaN) {
+				throw new Error(undefined);
+			}
+
+			return (this.result);
+		} catch(err) {
+			alert(err);
+			return(err);
+		};
+	};
+
+	/*
+	Execute special functions. 
+
+	@param {string} operation The function name to execute.
+	@param {string} passthrough The value to pass through.
+	*/
+	run (operation, passthrough) {
+		if ((operation) ? operation.trim() : false) {
+			switch (operation) {
+				case `AC`:
+					this.expression = [];
+					break;
+				case `=`:
+					this.result = this.calculate((passthrough) ? passthrough : this.expression);
+					this.expression = [this.result];
+					break;
+				default:
+					break;
+			};
+		};
+	}
+
+	/*
+	Allow the users to input data.
+	*/
+	interactive() {
+		while (true) {
+			this.input = prompt((this.expression.length) ? this.expression.join(` `) : `0`);
+
+			// Input number first. Usually, this can be determined if the number length is the same as the operand length.
+			if ((this.input) ? this.input.trim() : false) {
+				this.input = this.input.trim();
+
+				if ((this.#config[`operands`].includes(this.input)) || (!(this.#config[`functions`].includes(this.input)))) {
+					if (!((this.#config[`operands`].includes(this.input)) || (this.#config[`order`].includes(this.input)))) {
+						try {
+							this.input = parseFloat(this.input);
+						} catch(err) {};
+					};
+
+					// Check if the last item is an operand. 
+					if ((this.expression.length && (!(this.#config[`order`].includes(this.input)))) ? (((typeof this.input).includes(`number`)) ? ((typeof this.expression[this.expression.length - 1]).includes(`number`)) : this.#config[`operands`].includes(this.expression[this.expression.length - 1])) : false) {
+						this.expression[this.expression.length - 1] = this.input;
+					} else {
+						this.expression.push(this.input);
+					};
+					
+				} else if (this.#config[`functions`].includes(this.input)) {
+					this.run(this.input);
+				}
+			} else {
+				break;
+			}
+
+			delete this.input;
+		}
+	}
+
+	constructor() {
+		this.#config = {};
+		this.#config[`operands`] = [`+`, `-`, `*`, `/`, `%`,  `^`];
+		this.#config[`order`] = [`(`, `)`];
+		this.#config[`functions`] = [`AC`, `=`];
+	};
+};
+
+
+function main() {
+	let INSTANCE = new Calculator();
+	INSTANCE.interactive();
+};
+
+main();