JavaScript

Scenarios

To use JavaScript to call an API through App authentication, obtain the JavaScript SDK, create a new project, and then call the API by referring to the API calling example.

This section uses IntelliJ IDEA 2018.3.5 as an example to describe how to set up a Node.js development environment.

Preparing the Environment

You have obtained the domain name, request URL, and request method of the API to be called, and the AppKey and AppSecret of the App for calling the API. For more information, see Preparation.
You have installed the Node.js programming language. If not, download the Node.js installation package from the official Node.js website and install it.
After Node.js is installed, run the npm command to install the moment and moment-timezone modules.
```
npm install moment --save
npm install moment-timezone --save
```
You have installed IntelliJ IDEA. If not, download IntelliJ IDEA from the official IntelliJ IDEA website and install it.
You have installed the Node.js plug-in on IntelliJ IDEA. If not, install the Python plug-in according to Figure 1.
Figure 1 Installing the Node.js plug-in

Obtaining the SDK

Log in to the DataArts Studio console.
Click DataArts DataService.
In the navigation pane, choose DataArts DataService Exclusive > SDKs.
On the SDKs page, download the SDK package.

Verify integrity of the SDK package. In Windows, open the CLI and run the following command to generate the SHA-256 value of the downloaded SDK package. In the command, D:\java-sdk.zip is an example local path and name of the SDK package. Replace it with the actual value.

certutil -hashfile D:\java-sdk.zip SHA256

The following is an example command output:

SHA-256 hash value of D:\java-sdk.zip
3a86f1ba249a00727db506e4075ec9630e6cf74f312bddf6c3901c9d0786f53e
CertUtil: -hashfile command executed.
3a86f1ba249a00727db506e4075ec9630e6cf74f312bddf6c3901c9d0786f53e

Compare the SHA-256 value of the downloaded SDK package with that provided in the following table. If they are the same, no tampering or packet loss occurred during the package download.

**Table 1** SDK packages and the corresponding SHA-256 values
Language	SHA-256 Value of the SDK Package
Java	3a86f1ba249a00727db506e4075ec9630e6cf74f312bddf6c3901c9d0786f53e
Go	23734867eae2e7ef61427c64aa33aa89512571946f2f43a1a5fef5e801e3129f
Python	57636d8bacc459cab9dc08c70d01ccc42391ace60e6960c4e947566da1dc5d26
C#	e5a3b677f75c28ba3f1e16645d8171f7b6f34a42143f8a32a68bb18719b5e65d
JavaScript	442ac2fcb41d84525dc0139ec3f05d190e4e337cdbcdfdfc82a09d79d2ecd25e
PHP	2cc76bd2ecd48f00899d18b0f76d05ce2623065180f111c3f70ac14ddf0506f3
C++	2a54c3f2486d562ea6af1384eca40b301918bdc02f98bbf2c114f282dc059c00
C	4957556c108e0174d55b4b8d720f296967a9367ca54010792b1b3de039b87363
Android	0fdcc6fd93a68dce5c3e1b8e6370cc9340429cabfb0f268c3f9e5ea05238ae96

Obtain the ApiGateway-javascript-sdk.zip package. The following table shows the files decompressed from the package.

Name	Description
signer.js	SDK code
node_demo.js	Node.js sample code
demo.html	Browser sample code
demo_require.html	Browser sample code (loaded using require)
test.js	Test case
js\hmac-sha256.js	Dependencies
js\moment.min.js
js\moment-timezone-with-data.min.js
licenses\license-crypto-js	Third-party licenses
licenses\license-moment
licenses\license-moment-timezone
licenses\license-node

Creating a Project

Start IntelliJ IDEA and choose File > New > Project.
In the New Project dialog box, choose Static Web and click Next.

Figure 2 New Project
Click ..., select the directory where the SDK is decompressed, and click Finish.

Figure 3 Selecting the SDK directory after decompression
View the directory structure shown in the following figure.

Figure 4 Directory structure of the new project
- node_demo.js: Sample code in Node.js. Modify the parameters in the sample code as required. For details about the sample code, see API Calling Example (Node.js).
Click Edit Configurations.

Figure 5 Edit Configurations
Click + and select Node.js.

Figure 6 Selecting Node.js
Set JavaScript file to node_demo.js and click OK.

Figure 7 Selecting node_demo.js

API Calling Example (Node.js)

Import signer.js to your project.

      
           var signer = require('./signer')
var http = require('http')

Generate a new signer and enter the AppKey and AppSecret.

      
           // Coded or plaintext AK and SK pose significant security risks. To ensure security, encrypt your AK and SK, store them in configuration files or environment variables, and decrypt them when needed.
// In this example, the AK and SK stored in the environment variables are used for identity authentication. Before running this example, configure environment variables SDK_AK and SDK_SK in the local environment.
var ak = process.env.SDK_AK;
var sk = process.env.SDK_SK;

var sig = new signer.Signer();
sig.Key = ak;
sig.Secret = sk;

Generate a request, and specify the method, request URI, and request body.

      
           var r = new signer.HttpRequest("POST", "{apig-endpoint}/app1?a=1");
r.body = '{"a":1}'

Add a header to the request. The header contains specific parameters. Add other headers to be signed as necessary.
1

r.headers = { "x-stage":"RELEASE", "name":"value"}

Execute the following function to generate HTTP(s) request parameters, and add the X-Sdk-Date and Authorization headers for signing the request: Then, add the x-Authorization header to the request. The value of the x-Authorization header is the same as that of the Authorization header.

      
           var opt = sig.Sign(r)
opt.headers["x-Authorization"] = opt.headers["Authorization"]

Access the API and view the access result. If you access the API using HTTPS, change http.request to https.request.

      
           var req=http.request(opt, function(res){
        console.log(res.statusCode)  
        res.on("data",	function(chunk){
		console.log(chunk.toString())
	})
})
req.on("error",function(err){
	console.log(err.message)
})
req.write(r.body)
req.end()