Get Programming with JavaScript

Get Programming with JavaScript - Listing 3.11

Listing 3.11 - Using a property in a calculation

var player1;

player1 = {
    name: "Max",
    score: 0
};

console.log(player1.name + " has scored " + player1.score);

player1.score = player1.score + 50;

console.log(player1.name + " has scored " + player1.score);

Further Adventures

Listing 3.11 - Using a property in a calculation - Task 1

Write code to increase player1's score by 10%.

var player1;

player1 = {
    name: "Max",
    score: 0
};

console.log(player1.name + " has scored " + player1.score);

player1.score = player1.score + 50;

console.log(player1.name + " has scored " + player1.score);

player1.score = player1.score * 1.1;    // increase player1's score by 10%

Use the * symbol to multiply numbers together. Multiply a number by 1.1 to increase it by 10%.

Listing 3.11 - Using a property in a calculation - Task 2

Add a second player.

var player1;
var player2;    // declare a second variable

player1 = {
    name: "Max",
    score: 0
};

player2 = {            // create a second
    name: "Kandra",    // player and assign
    score: 40          // it to the player2
};                     // variable

console.log(player1.name + " has scored " + player1.score);

player1.score = player1.score + 50;

console.log(player1.name + " has scored " + player1.score);

player1.score = player1.score * 1.1;

Listing 3.11 - Using a property in a calculation - Task 3

Use the players' properties to find the sum of their scores and log it to the console, along with an appropriate message that includes their names.

var player1;
var player2;

player1 = {
    name: "Max",
    score: 0
};

player2 = {
    name: "Kandra",
    score: 40
};

console.log(player1.name + " has scored " + player1.score);

player1.score = player1.score + 50;

console.log(player1.name + " has scored " + player1.score);

player1.score = player1.score * 1.1;

// Log a message including the sum of scores
console.log("The sum of scores for " + player1.name + " and " + player2.name + " is " + (player1.score + player2.score));

The + symbol does double-duty: it concatenates strings and it adds numbers. Use parentheses to ensure the numbers are added before the result is concatenated to the string.

See what happens if you remove the parentheses around player1.score + player2.score.