1# Usage of npm 2 3### Introduction 4 5This sample shows how npm references third-party JS class libraries (mathjs and dayjs) and local libraries. The display effect is as follows: 6 7 8 9### Concepts 10 11npm: a package manager that references third-party JS class libraries and local libraries. 12 13##### Importing a Third-Party JS Class Library 14 151. Open the **Terminal** window and run the following command to go to the **entry** directory: 16 17 cd entry 18 192. Run the following command to install a third-party library package. In this example, **dayjs** is being installed. 20 21 npm install dayjs --save 22 233. Import the third-party library package in the corresponding .ets file. 24 25 import dayjs from 'dayjs' 26 27##### Creating a Local Library 28 291. Right-click the project name, choose **New > Module**, click **Ohos Library** on the **Choose Your Ability Template** page displayed, enter the module name, and click **Finish**. 30 312. In the new module directory, edit the **name** attribute in the **Package.json** file, for example, **name:@ohos/library**. 32 333. In the **entry** directory, add the new module as a dependency to the **dependencies** attribute in the **Package.json** file, for example, **"@ohos/library": "../library"**. 34 354. In the new **Module** directory, add the common components or interfaces to be exported to **Index.ets** file. 36 375. In the **entry** directory, import the common component or interface in the new module to be used, for example, **import {ThirdTitleBar} from '@ohos/library'**. 38 39### Required Permissions 40 41N/A 42 43### Usage 44 451. The home page of the sample app shows the application of mathjs. After you touch **Click generate verification code**, a six-digit random verification code is generated in the lower part. If you touch the button again, a new verification code is displayed. You can touch **Back** to exit the app. 46 472. Touch **Next page**, and the application of dayjs is displayed. Enter the date to be calculated, enter either the number of days backwards or forwards, or both of them, and touch **Confirm**. The calculation result is displayed in the lower part. You can touch **Back** to return to the mathjs application page. 48 493. Touch **Next page**, and the application of the local library is displayed. Enter two strings as prompted and touch **Confirm**. The string after concatenation is displayed in the lower part. You can touch **Back** to return to the dayjs application page. 50 51### Constraints 52 531. This sample can only be run on standard-system devices. 54 552. In this sample, only open-source pure logic third-party libraries can be imported. The **format** method in dayjs is not supported. 56 573. This sample is based on the stage model, which is supported from API version 9. 58 594. DevEco Studio 3.0 Beta4 (Build version: 3.0.0.992, built on July 14, 2022) must be used. 60
