Example Typescript project - veracity-dev/github-xlsx GitHub Wiki

CLI Calculator Tutorial - Typescript Project for Beginners

Tutorial

import { question } from "readline-sync";
type Operator = '+' | '-' | '*' | '/';

function main():void{
    const firstStr: string = question("Enter first number:\n");
    const operator: string = question("Enter Operator:\n");
    const secondStr: string = question("Enter Second number:\n");
    
    const validInput: boolean = isNumber(firstStr)&&isOperator(operator) && isNumber(secondStr);
    console.log(validInput);

    if (validInput){
        console.log('is valid');
        const firstNum: number = parseInt(firstStr);
        const secondNum: number = parseInt(secondStr);
        const result = calculate(firstNum,operator as Operator,secondNum);
        console.log(result);
    }
    else{
        console.log('\ninvalid input\n');
        main();
    }
}
function isNumber(str: string): boolean{
    const maybeNum = parseInt(str); 
    const isNum: boolean = Boolean(maybeNum);
    return isNum;
}

function isOperator(operator: string): boolean{
    switch(operator){
        case '+':
        case '-':
        case '-':
        case '-':
            return true;
        default:
            return false;
    }
    
}

function calculate(firstNum:number,operator:Operator,secondNum:number){
    switch(operator){
        case '+':
            return firstNum + secondNum;
        case '-':
            return firstNum - secondNum;
        case '*':
            return firstNum * secondNum;
        case '/':
            return firstNum / secondNum;

    }
}
main();

Use the below commands to Convert and run the code

Below code is used to convert the TypeScript to JavaScript

tsc index.ts

index.ts is used because the above TypeScript code is written in an index.ts file

To Run the code

node index.js

Sample output is shown below