[TypeScript] TypeScript Grammar - 06~07

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6.  Functions

This Posting contains how to make functinos in TypeScript

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6_01.  Functions_return type

When contains void

function add(n1: number, n2: number):void{
	console.log(n1 + n2);
}

When contains return type

function add(n1: number, n2: number):void{
	return (n1 + n2);
}

function time(minute: number):boolean{
	return num = 60;
}

function functionTest (x: number): number{
	return x*3;
}

functionTest(2);
functionTest('10'); // not number value, error

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6_02.  Functions_with optional

import { log } from "console";

function hello(name ?: string){
	return `hello, ${name || "world"}`;
}

const result = hello();
const result2 = hello("Sam Rider");

log(result); // hello, world
log(result2); // hello, Sam Rider

I think that part of "${name || 'world'}" may be show 'world' when the name's type is different from the setting

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7.  Loop

Maybe you are familiar with this, because in Python, there is a 'for loop' and it is similar

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7_01.  Loop_let ... in

array

import { log } from 'console';

let list: string[] = ['test1', 'test2', 'test3'];

for (let i in list){
	log(i, list[i]);
}

Q. Can we do the type designation on the following list?

 

import { log } from 'console';

let animals: any = {a: 'rat', b: 'cat', c: 'tiger'}
for (let anim in animals){
	log(anim, animals[anim]);
}

A. Of course No

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7_02.  Loop_let ... of

import { log } from 'console';

let str: string = "hello";

for (const a of str){
	log(a);
}

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End

 

 

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[TypeScript] TypeScript Grammar - 08