Functions

Before we start writing the bot script, we will create several functions that will implement the mechanics of the game.

Main functions of the game

Create responseCity.js file in the src folder. It will contain the game functions that we will call from the script:

• returning a city that starts with the last letter of the previously named city;
• searching for the entered city by key;
• checking if the entered city is in the city list;
• checking if the last letter of the previous city matches the first letter of the entered city;
• returning a random key of the city;
• checking if a user has entered a full city name.

function responseCity(parseTree, keys, cities) {
    var city = parseTree._City.name
    var letter = city[city.length - 1]
    var response = 0

    keys.forEach(function(elem) {
        if (cities[elem].value.name[0].toLowerCase() == letter) {
            response = elem
        }
    })

    if (response == 0) {
        letter = city[city.length - 2]
        keys.forEach(function(elem) {
        if (cities[elem].value.name[0].toLowerCase() == letter) {
            response = elem
        }
    })
    }
    return response
}

function findByName(city, keys, cities) {
    var response = 0
    var i = 0

    keys.forEach(function(elem) {
        if (cities[elem].value.name == city) {
            response = i
        }
        i++
    })

    return response
}

function checkCity(parseTree, keys, cities) {
    var city = parseTree._City.name
    var response = false

    keys.forEach(function(elem) {
        if (cities[elem].value.name == city) {
            response = true
        }
    })
    return response;
}

function checkLetter(playerCity, botCity) {
    var response = false
    if ((playerCity[0].toLowerCase() == botCity[botCity.length - 1])
        || (playerCity[0].toLowerCase() == botCity[botCity.length - 2])) {
        response = true
    }
    return response
}

function chooseRandCityKey(keys) {
    var i = 0
    keys.forEach(function(elem) {
        i++
    })
    return  $jsapi.random(i);
}

function isAFullNameOfCity() {
    return $jsapi.context().parseTree._City.name.toUpperCase() == $jsapi.context().parseTree.text.toUpperCase();
}

In the project, we will use city/cities-en.csv additional module that contains a list of more than 8500 city names. We will take a look at how this module is used in the Project files section.

Each city in the list has the following structure:

6614;New York City,New York, NY;
{
    "name":"New York City",
    "lat":40.71427,
    "lon":-74.00597,
    "country":"US",
    "timezone":"America/New_York",
    "population":8175133
    }

We will only use id and name values.

tip

Learn more about using JS-files in the project

Functions description

responseCity ()

The responseCity() function returns a city that starts from the last letter of the entered city. When the city list runs out of city names starting with a certain letter, then the function returns a city starting with the second to last letter.

function responseCity(parseTree, keys, cities) {
    // save the entered city name
    var city = parseTree._City.name
    // take the last letter of the entered city
    var letter = city[city.length - 1]
    // initialize the key of the city
    var response = 0

    /* looking through the elements of the city list
    until we find a city that starts with the last letter of the previous city*/
    keys.forEach(function(elem) {
        if (cities[elem].value.name[0].toLowerCase() == letter) {
            response = elem
        }
    })

    /* if the city list runs out of city names starting with a certain letter,
    then use the second to last letter*/
    if (response == 0) {
        letter = city[city.length - 2]
        keys.forEach(function(elem) {
        if (cities[elem].value.name[0].toLowerCase() == letter) {
            response = elem
        }
    })
    }
    return response
}

findByName ()

The findByName() function searches for the named city in the city/cities-en.csv file.

/* we will call this function from the script to remove the entered city from the list*/
function findByName(city, keys, cities) {
    // initialize the key of the city
    var response = 0
    var i = 0

    // looking through the elements of the list until we find the entered city
    keys.forEach(function(elem) {
        if (cities[elem].value.name == city) {
            response = i
        }
        i++
    })

    return response
}

checkCity ()

The checkCity() function checks if the entered city is in the city/cities-en.csv list. Returns true or false.

function checkCity(parseTree, keys, cities) {
    // save the entered city name
    var city = parseTree._City.name
    var response = false

    // looking through the elements of the list until we find the entered city
    keys.forEach(function(elem) {
        if (cities[elem].value.name == city) {
            response = true
        }
    })
    return response;
}

checkLetter ()

The checkLetter() function checks if the first letter of the city the user has entered matches the last or the second to last letter of the city the bot has entered.

function checkLetter(playerCity, botCity) {
    var response = false
    /* true, if the first letter of the city the user has entered
     matches the last letter of the city the bot has entered */
    if ((playerCity[0].toLowerCase() == botCity[botCity.length - 1])
        || (playerCity[0].toLowerCase() == botCity[botCity.length - 2])) {
        response = true
    }
    return response
}

chooseRandCityKey ()

The chooseRandCityKey() function returns a random key number of the city. The function is called from the script when the bot starts the game.

function chooseRandCityKey(keys) {
    return $jsapi.random(keys.length);
}

isAFullNameOfCity ()

The isAFullNameOfCity() function checks if the user has entered a full city name. Returns true or false.

function isAFullNameOfCity() {
    return $jsapi.context().parseTree._City.name.toUpperCase() == $jsapi.context().parseTree.text.toUpperCase();
}

Next, move on to creating the configuration file and the script.