76 lines
2.6 KiB
Markdown
76 lines
2.6 KiB
Markdown
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---
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id: 598f48a36c8c40764b4e52b3
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title: Prevent Object Mutation
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localeTitle: Prevenir la mutación de objetos
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challengeType: 1
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---
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## Description
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<section id='description'>
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Como se vio en el desafío anterior, la declaración <code>const</code> por sí sola no protege realmente sus datos de la mutación. Para garantizar que sus datos no cambien, JavaScript proporciona una función <code>Object.freeze</code> para evitar la mutación de datos.
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Una vez que el objeto está congelado, ya no puede agregar, actualizar o eliminar propiedades de él. Cualquier intento de cambiar el objeto será rechazado sin un error.
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<blockquote>let obj = {<br> name:"FreeCodeCamp",<br> review:"Awesome"<br>};<br>Object.freeze(obj);<br>obj.review = "bad"; //will be ignored. Mutation not allowed<br>obj.newProp = "Test"; // will be ignored. Mutation not allowed<br>console.log(obj); <br>// { name: "FreeCodeCamp", review:"Awesome"}</blockquote>
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</section>
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## Instructions
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<section id='instructions'>
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En este desafío, <code>Object.freeze</code> para evitar que <code>Object.freeze</code> las constantes matemáticas. <code>MATH_CONSTANTS</code> congelar el objeto <code>MATH_CONSTANTS</code> para que nadie pueda alterar el valor de <code>PI</code> , agregar o eliminar propiedades.
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</section>
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## Tests
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<section id='tests'>
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```yml
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tests:
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- text: No reemplace la palabra clave <code>const</code> .
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testString: 'getUserInput => assert(getUserInput("index").match(/const/g), "Do not replace <code>const</code> keyword.");'
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- text: <code>MATH_CONSTANTS</code> debe ser una variable constante (usando <code>const</code> ).
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testString: 'getUserInput => assert(getUserInput("index").match(/const\s+MATH_CONSTANTS/g), "<code>MATH_CONSTANTS</code> should be a constant variable (by using <code>const</code>).");'
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- text: No cambie los <code>MATH_CONSTANTS</code> originales.
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testString: 'getUserInput => assert(getUserInput("index").match(/const\s+MATH_CONSTANTS\s+=\s+{\s+PI:\s+3.14\s+};/g), "Do not change original <code>MATH_CONSTANTS</code>.");'
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- text: <code>PI</code> es igual a <code>3.14</code> .
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testString: 'assert(PI === 3.14, "<code>PI</code> equals <code>3.14</code>.");'
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```
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</section>
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## Challenge Seed
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<section id='challengeSeed'>
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<div id='js-seed'>
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```js
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function freezeObj() {
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"use strict";
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const MATH_CONSTANTS = {
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PI: 3.14
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};
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// change code below this line
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// change code above this line
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try {
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MATH_CONSTANTS.PI = 99;
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} catch( ex ) {
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console.log(ex);
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}
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return MATH_CONSTANTS.PI;
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}
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const PI = freezeObj();
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```
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</div>
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</section>
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## Solution
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<section id='solution'>
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```js
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// solution required
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```
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</section>
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