Booleans and Control Flow
Boolean values are a core primitive type in JavaScript. A boolean can only be true or false, and is used to represent logical states or conditions. Booleans are essential for controlling the flow of your code, especially in decision-making structures like if statements. When you want your program to take different actions based on certain conditions, you will rely on boolean values to determine which path to follow. For example, you might want to show a special message if a user is logged in (true), or hide it if they are not (false). Understanding booleans is key to making your programs interactive and responsive to different situations.
12345678910// Declaring boolean variables let isLoggedIn = true; let hasAdminAccess = false; // Using booleans in a simple condition if (isLoggedIn) { console.log("Welcome back!"); } else { console.log("Please log in."); }
In JavaScript, not only true and false are used in conditional statements. Every value in JavaScript is either truthy or falsy when evaluated in a boolean context. Falsy values are values that are considered false when used in conditions. The main falsy values are: false, 0, "" (empty string), null, undefined, and NaN. Any value that is not falsy is considered truthy. For instance, the number 1, any non-empty string like "hello", and objects or arrays are all truthy. This means that even if you do not explicitly use true or false, JavaScript will convert other values to either true or false when evaluating conditions. Being aware of which values are truthy or falsy helps you write more predictable and bug-free code.
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What are some examples of truthy values in JavaScript?
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Why does JavaScript treat some values as truthy and others as falsy?
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Boolean values are a core primitive type in JavaScript. A boolean can only be true or false, and is used to represent logical states or conditions. Booleans are essential for controlling the flow of your code, especially in decision-making structures like if statements. When you want your program to take different actions based on certain conditions, you will rely on boolean values to determine which path to follow. For example, you might want to show a special message if a user is logged in (true), or hide it if they are not (false). Understanding booleans is key to making your programs interactive and responsive to different situations.
12345678910// Declaring boolean variables let isLoggedIn = true; let hasAdminAccess = false; // Using booleans in a simple condition if (isLoggedIn) { console.log("Welcome back!"); } else { console.log("Please log in."); }
In JavaScript, not only true and false are used in conditional statements. Every value in JavaScript is either truthy or falsy when evaluated in a boolean context. Falsy values are values that are considered false when used in conditions. The main falsy values are: false, 0, "" (empty string), null, undefined, and NaN. Any value that is not falsy is considered truthy. For instance, the number 1, any non-empty string like "hello", and objects or arrays are all truthy. This means that even if you do not explicitly use true or false, JavaScript will convert other values to either true or false when evaluating conditions. Being aware of which values are truthy or falsy helps you write more predictable and bug-free code.
Merci pour vos commentaires !
