JavaScript flow-node

5 minute read

Overview

The JavaScript plugin, @axway/api-builder-plugin-fn-javascript, allows the user to execute JavaScript code inside a Flow.

To install the JavaScript plugin, execute the following command:

npm install --no-optional @axway/api-builder-plugin-fn-javascript

For additional getting started information, refer to the Getting Started With API Builder.

Methods

The following sections provide details of the JavaScript flow-node Execute method.

Execute

Allows the execution of JavaScript code and returns the result of the execution as the flow-node’s output.

Flow-node’s parameters

Parameter Type Description Configuration selection Required
Code string A JavaScript function body. Supports `await` and returning promises. Selector, String Yes
Data any The value to apply as the `data` argument to the JavaScript code. For objects and arrays, `data` is passed by reference. Any No
Parameter: Code

The Code parameter is where you define the JavaScript you would like to execute. The Code should be provided as a String. The Data parameter is fed into the code snippet as the first argument, data. The second argument of the code, logger, is the API Builder logger.

Parameter: Data

The Data parameter refers to content which is passed to the JavaScript code. The content is passed as an argument in the code as data. The parameter can be any data type. For example, you could use $ Selector to access the entire context, or limit it to a specific subset (e.g. to access parameters as parameters - $.params).

Outputs

Output Type Description Save output value as:
Next any The data returned by the code snippet. If returning a promise, this will be the data that the promise resolves with. $.result
Error any This output is triggered if the code snippet throws an error or returns a promise which rejects. The output value an object with the error message, or the rejected value. $.error

How to use the JavaScript plugin

After the installation of the JavaScript plugin and editing a Flow, you will find the JavaScript flow-node in the Core section:

image2021-6-30_11_11_5

You can drag and drop the JavaScript flow-node into the Flow Graph to expand its details:

image2021-6-30_11_10_13

Example 1 - Greet Flow

Here is how you could use the JavaScript flow-node to achieve the same functionality as our Greet Flow example:

First, you would need to determine the data you would like to pass to your function. For the Greet Flow you will need both the $.config, as the salutation is stored there, and the user’s name, which comes from $.params.

So let’s pass the entire context with the $ selector and use JavaScript code to format the message as we have seen in the Greet Flow.

image2019-7-5_9_40_52

We could use a simple template literal to construct the message:

image2021-5-18_12_14_56

Let’s hook everything up as we have seen before to the success node and bad request node.

Screen_Shot_2019-07-04_at_15.20.26

Make sure the outputs of the JavaScript flow-node are correctly used within the HTTP flow-nodes. As described above, the default outputs are $.result and $.error:

Screen_Shot_2019-07-04_at_15.21.17 image2019-7-5_9_41_40

You could invoke your newly created flow through the debugger: debugger

Which would return the already familiar salutation:

Screen_Shot_2019-07-03_at_18.24.39

Example 2 - Logging

The JavaScript flow-node can also make use of the API Builder logger. You can see the logger as the second argument to the Code function. As with anything that uses the API Builder logger, only logs at or above the configured LOG_LEVEL of the service will be output to the terminal. See Logging for more details.

Here is how you can add extra debugging to your flow:

This example flow-node calculates the product of the provided array of numbers.

image2021-5-18_12_36_22

1621337798796 DEBUG [request-id: 9abdf0c2-efb0-4d85-b6cb-3746ea0133f1] Waiting: Calculate product (javascript.1)
1621337798796 DEBUG [request-id: 9abdf0c2-efb0-4d85-b6cb-3746ea0133f1] Invoking: Calculate product (javascript.1), method: Execute
1621337798798 DEBUG [request-id: 9abdf0c2-efb0-4d85-b6cb-3746ea0133f1]   Calculate product (javascript.1) route: []
1621337798798 DEBUG [request-id: 9abdf0c2-efb0-4d85-b6cb-3746ea0133f1]   Calculate product (javascript.1) writing 120780 to ctx as: $.response

Unfortunately, when debugging, we do not see which numbers are being calculated and only the result. We will add a debug log to show what is going on!

image2021-5-18_12_38_33

1621337924647 DEBUG [request-id: 29011c0a-317c-456a-ac63-0dfa9f8a7f07] Waiting: Calculate product (javascript.1)
1621337924647 DEBUG [request-id: 29011c0a-317c-456a-ac63-0dfa9f8a7f07] Invoking: Calculate product (javascript.1), method: Execute
1621337924648 DEBUG [request-id: 29011c0a-317c-456a-ac63-0dfa9f8a7f07]   Calculate product (javascript.1) Calculating: 1 * 5 * 99 * 244
1621337924648 DEBUG [request-id: 29011c0a-317c-456a-ac63-0dfa9f8a7f07]   Calculate product (javascript.1) route: []
1621337924648 DEBUG [request-id: 29011c0a-317c-456a-ac63-0dfa9f8a7f07]   Calculate product (javascript.1) writing 120780 to ctx as: $.response

Example 3 - Format Object

Input Code Output
data = {
“firstName”: “Bruce”,
“lastName”: “Wayne”,
“heroName”: “Batman”
};		 // Maps a hero name to the Universe the character belongs to
const heroNamesToUniverseMapper = {
‘Batman’: ‘DC’,
‘Flash’: ‘DC’,
‘Spiderman’: ‘Marvel’,
‘Iron Man’: ‘Marvel’
};

return {
heroName: data.heroName,
secretName: data.firstName + ’ ’ + data.lastName,
universe: heroNamesToUniverseMapper[data.heroName]

Example 4 - String Concatenation

Input Code Output
data = {
“firstName”: “Bruce”,
“lastName”: “Wayne”
};		 return data.firstName + ’ ’ + data.lastName; “Bruce Wayne”
data = {
“firstName”: “Bruce”,
“lastName”: “Wayne”
};		 return `${data.firstName} ${data.lastName}`; “Bruce Wayne”

Example 5 - Processing Data

Input Code Output
data = [“1”,“2”,“3”,“4”,“5”]; let result = 0;

data.forEach(function(element) {
const number = parseInt(element);
if(number % 2 == 0){
result += number;
}
});

return result;		 6
data = [“1”,“2”,“3”,“4”,“5”]; return data.map(item => parseInt(item))
.filter(number => number % 2 == 0)
.reduce((sum, number) => sum + number);		 6

Example 6 - Object Manipulation - Combining two objects

Input Code Output
data = {
“birthYear”: 1989,
“name”: “Peter Parker”
};		 const companyDetails = {
company: ‘Axway’,
companyAddress: ‘Phoenix, US’
};

return Object.assign(data, companyDetails);		 {
“birthYear”: 1989,
“name”: “Peter Parker”,
“company”: “Axway”,
“companyAddress”: “Phoenix, US”
}

Example 7 - Object Manipulation - Merging with spread

Input Code Output
data = {
“birthYear”: 1989,
“name”: “Peter Parker”
};		 return {
…data,

company: ‘Axway’,
companyAddress: ‘Phoenix, US’
};		 { “birthYear”: 1989,
“name”: “Peter Parker”,
“company”: “Axway”,
“companyAddress”: “Phoenix, US”
}
Last modified March 10, 2022: Ikeja release notes (#66) (d0d0dd6)