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JavaScript. W3Schools en español. Lecciones para principiantes

Ua En De Fr Ru

JavaScript if

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La declaración if de JavaScript

Utilice la declaración if de JavaScript para ejecutar un bloque de código cuando una condición es verdadera.

Sintaxis

if (condition) {
  //  bloque de código que se ejecutará si se cumple la condición true
}

Tenga en cuenta que if está en minúsculas. Las mayúsculas (If o IF) generarán un error de JavaScript.

Ejemplo

Haz un saludo de "Good day" si la hora es menor de las 18:00:

if (hour < 18) {
  greeting = "Good day";
}

El resultado del saludo será:

Try it Yourself »

Ejemplos

let age = 18;
let text = "You can Not drive";

if (age >= 18) {
  text = "You can drive");
}
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let age = 16;
let text = "You can Not drive";

if (age >= 18) {
  text = "You can drive");
}
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Anidado if

Puede utilizar una declaración if dentro de otra declaración if:

Ejemplo

let age = 16;
let country = "USA";
let text = "You can Not drive!";

if (country == "USA") {
  if (age >= 16) {
    text = "You can drive!";
  }
}
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Las declaraciones if anidadas pueden hacer que su código sea más complejo.

Una mejor solución es utilizar el operador lógico AND:

Ejemplo

let age = 16;
let country = "USA";
let text = "You can Not drive!";

if (country == "USA" && age >= 16) {
  text = "You can drive!";
}
Try it Yourself »
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