160 lines
3.0 KiB
Markdown
160 lines
3.0 KiB
Markdown
---
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id: 56bbb991ad1ed5201cd392d0
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title: Build JavaScript Objects
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challengeType: 1
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videoUrl: 'https://scrimba.com/c/cWGkbtd'
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forumTopicId: 16769
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dashedName: build-javascript-objects
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---
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# --description--
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You may have heard the term `object` before.
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Objects are similar to `arrays`, except that instead of using indexes to access and modify their data, you access the data in objects through what are called `properties`.
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Objects are useful for storing data in a structured way, and can represent real world objects, like a cat.
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Here's a sample cat object:
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```js
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var cat = {
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"name": "Whiskers",
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"legs": 4,
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"tails": 1,
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"enemies": ["Water", "Dogs"]
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};
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```
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In this example, all the properties are stored as strings, such as - `name`, `legs`, and `tails`. However, you can also use numbers as properties. You can even omit the quotes for single-word string properties, as follows:
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```js
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var anotherObject = {
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make: "Ford",
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5: "five",
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"model": "focus"
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};
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```
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However, if your object has any non-string properties, JavaScript will automatically typecast them as strings.
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# --instructions--
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Make an object that represents a dog called `myDog` which contains the properties `name` (a string), `legs`, `tails` and `friends`.
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You can set these object properties to whatever values you want, as long as `name` is a string, `legs` and `tails` are numbers, and `friends` is an array.
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# --hints--
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`myDog` should contain the property `name` and it should be a `string`.
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```js
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assert(
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(function (z) {
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if (
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z.hasOwnProperty('name') &&
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z.name !== undefined &&
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typeof z.name === 'string'
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) {
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return true;
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} else {
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return false;
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}
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})(myDog)
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);
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```
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`myDog` should contain the property `legs` and it should be a `number`.
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```js
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assert(
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(function (z) {
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if (
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z.hasOwnProperty('legs') &&
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z.legs !== undefined &&
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typeof z.legs === 'number'
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) {
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return true;
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} else {
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return false;
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}
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})(myDog)
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);
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```
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`myDog` should contain the property `tails` and it should be a `number`.
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```js
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assert(
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(function (z) {
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if (
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z.hasOwnProperty('tails') &&
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z.tails !== undefined &&
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typeof z.tails === 'number'
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) {
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return true;
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} else {
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return false;
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}
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})(myDog)
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);
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```
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`myDog` should contain the property `friends` and it should be an `array`.
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```js
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assert(
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(function (z) {
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if (
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z.hasOwnProperty('friends') &&
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z.friends !== undefined &&
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Array.isArray(z.friends)
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) {
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return true;
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} else {
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return false;
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}
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})(myDog)
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);
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```
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`myDog` should only contain all the given properties.
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```js
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assert(
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(function (z) {
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return Object.keys(z).length === 4;
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})(myDog)
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);
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```
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# --seed--
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## --after-user-code--
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```js
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(function(z){return z;})(myDog);
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```
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## --seed-contents--
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```js
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var myDog = {
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// Only change code below this line
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// Only change code above this line
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};
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```
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# --solutions--
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```js
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var myDog = {
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"name": "Camper",
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"legs": 4,
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"tails": 1,
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"friends": ["everything!"]
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};
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```
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