Truthy and Falsy Values in JS

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In JavaScript, values are considered either “truthy” or “falsy” when evaluated in a Boolean context, such as in an if statement. Here is a list of all the falsy values and some common truthy values:

Falsy Values

There are exactly 8 falsy values in JavaScript:

1. false - The Boolean value false.
2. 0 - The number zero.
3. -0 - The number negative zero.
4. 0n - The BigInt zero.
5. "" - An empty string.
6. null - The absence of any value.
7. undefined - A variable that has been declared but not assigned a value.
8. NaN - The result of an invalid number operation (Not-a-Number).

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Truthy Values

All values that are not falsy are considered truthy. Here are some common examples of truthy values:

1. true - The Boolean value true.
2. Any non-zero number (e.g., 1, -1, 3.14).
3. Any non-empty string (e.g., "hello", “0”, "false").
4. Any object (e.g., {}, [], function() {}).
5. Any non-zero BigInt (e.g., 1n, -1n).
6. Infinity and -Infinity.

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Examples in Code

Here are some examples to illustrate truthy and falsy values in JavaScript:

if (false) {
  console.log("This will not run");
}
 
if (0) {
  console.log("This will not run");
}
 
if ("") {
  console.log("This will not run");
}
 
if (null) {
  console.log("This will not run");
}
 
if (undefined) {
  console.log("This will not run");
}
 
if (NaN) {
  console.log("This will not run");
}
 
if (true) {
  console.log("This will run");
}
 
if (1) {
  console.log("This will run");
}
 
if ("hello") {
  console.log("This will run");
}
 
if ({}) {
  console.log("This will run");
}
 
if ([]) {
  console.log("This will run");
}

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