Almost perfect water bottle solution + specs

Solution-water-bottle.js

let bottle_state = 0;
let extra_water= 0;


function read_water_level(bottle_state){
    console.log(bottle_state)
};

function drink_water(bottle_fullness, thirst_score, bottle_size) {
    let new_bottle_state = 0;
    let remaining_thirst = 0;
    if (bottle_fullness > 0 && thirst_score > 0 && bottle_fullness > thirst_score) {
        new_bottle_state = bottle_fullness - thirst_score;
        remaining_thirst = 0;

    } else if (bottle_fullness > 0 && thirst_score > 0 && bottle_fullness < thirst_score) {
        new_bottle_state = bottle_size;
        remaining_thirst = bottle_size - thirst_score;

    } else if (bottle_fullness == thirst_score) {
        new_bottle_state = 0;
        remaining_thirst = 0;
    } else {
        alert("Error");
    }
    return { new_bottle_state, remaining_thirst }; // es6 syntax 
};

console.log(drink_water(200, 100, 600));
        
    // = return {new_bottle_state: new_bottle_state, remaining_thirst: remaining_thirst}
};

function fill_bottle_with_water (bottle_fullness, bottle_size, water_purchased){
    let new_bottle_state_to_fill = 0;
    let water_left_over= 0;
        if (bottle_fullness > 0 && water_purchased > 0 && bottle_fullness< water_purchased || 
            bottle_fullness > 0 && water_purchased > 0 && bottle_fullness> water_purchased && water_purchased< bottle_size){
            new_bottle_state_to_fill = bottle_fullness + water_purchased;
            water_left_over = 0;
        }else if(bottle_fullness == bottle_size && water_purchased >= 0){
            new_bottle_state_to_fill = bottle_size;
            water_left_over= water_purchased;
        }else{
            alert("Error");
        }

    return {new_bottle_state_to_fill, water_left_over};
};

Specs-water-bottle

GLOBAL SCOPE:
    VARIABLE1: bottle_state
    Initialized: undefined
    Purpose: It shows water level in the bottle

    VARIABLE2: extra_water
    Initialized: undefined
    Purpose: It shows extra water

read_water_level: function
    ARGS:1

    bottle_state: DOM object
    PURPOSE: This function reads water level in the bottle
    BEHAVIOR: It calls bottle state of water 


drink_water: function
    ARGS: 2

    bottle_fullness: first argument
    PURPOSE: It shows the water level in the bottle at the initial stage

    thirst_score: second argument
    PURPOSE: It shows the thirst level

    bottle_size: third argument
    PURPOSE: It tells us the size of the bottle so we know the maximum quantity of water which can be filled into the bottle

    RETURN: An object 

    VARIABLE1: new_bottle_state
    Initialized: undefined

    VARIABLE2: remaining_thirst
    Initialized: undefined

    BEHAVIOR: This function calculates the new bottle state after drinking and our remaining thirst score. Then it returns an object with new variables mentioned before.

fill_bottle_with_water : function 
    ARGS: 3

    RETURN: An array

    bottle_fullness: first argument
    PURPOSE: It shows the water level in the bottle at the initial stage

    bottle_size: second argument
    PURPOSE: It tells us the size of the bottle

    water_purchased: third argument
    PURPOSE: It tells us the quantity of the purchased water

    VARIABLE1: new_bottle_state
    Initialized: undefined

    VARIABLE2: water_left_over
    Initialized: undefined

    BEHAVIOR: This function calculates the new bottle state after being filled with purchased water and the amount of water remaining after filling.


    

corrections aside, very good. you're now using behavior and purpose correctly