Javascript: 참조 투명성

const add = (x,y)=>x + y;

const multiply = (x)=>x * 4;

// add (3, 4) can be replaced by 7. - Referential Transparency.

multiply(add(3, 4)); 
> 28

multiply(add(3, 4));
> 28

const arr = [];
const add = (x,y)=>{
    const addition = x + y;
    arr.push(addition);
    return addition;
}

const multiply = (x)=>x * 4;

// Here, we can't replace add(3,4) with 7 as it affects the program
multiply(add(3, 4));
> 28

> multiply(add(3, 4));
28