# JAVASCRIPT_FUNCTION

The JAVASCRIPT_FUNCTION component allows to execute a custom JavaScript function and output its return value.

Examples of common use cases are:

Remove the first n characters from the barcode
Remove the last n characters from the barcode
Replace parts of the barcode
Extrapolate the data encoded inside the barcode
... and much more

You can use pretty much any combination of JavaScript methods to manipulate the strings. You can find the full list in the JavaScript String Methods.

# Examples

# Example 1: Remove the first character of a barcode

Initial barcode:  0897654321
Final output:      897654321

Steps:

Add a JAVASCRIPT_FUNCTION component just after the BARCODE component
Add the barcode.substr(1) code to the JAVASCRIPT_FUNCTION component
Enable the Skip output option of the BARCODE component

# Example 2: Extract a URL parameter from a QR Code

QR Code:        https://example.com/?user_id=123&tracking_id=RN015215156&order_id=456
Final output:   RN015215156

To achieve this result you can use the following code:

new URL(barcode).searchParams.get('tracking_id')

# Example 3: Extrapolate parts of the barcode

Initial barcode:  433-0132-22
Final output:         0132

Use the same procedure of Example 1, but use this JavaScript code instead:

barcode.split('-')[1]

# Using ChatGPT

If you're not familiar with JavaScript you can use AI to generate the code for you.

Example 1: Extract numeric parts

Barcode values such as ABCD1234CD needs to be transformed to 1234.

So we ask ChatGPT:

Strictly edit the match method of this JavaScript code so that barcode values such as ABCD1234CD are transformed to 1234: barcode.match(/(.*)/g)[0]
Edit this JavaScript fragment so that barcode values such as `ABCD1234CD` are transformed to `1234`: `barcode.match()`

View result

Example 2: Extract alphanumeric parts

To extract efg from a QR Code that contains abcd-efg-klmn we ask ChatGPT:

Call the correct method of this JavaScript code so that barcode values such as `abcd-efg-klmn` are transformed to `efg`.
Output only one line of code like this: `barcode.appropriateMethod()`

View result

# Advanced

# Multiline functions

Function that spans multiple lines must be written using the following syntax:

(function(barcode) {
    let result = '';
    /* Your code here */
    return result;
})(barcode)

Important notes:

Do not use single line comments // inside the function, only multiline comments /* */ are allowed.
You can inject variables by passing them as parameters of the function
Do not put the semicolon ; at the end of the function if you want to use the output

# Save global variables

You can store temporarary values to the window object, e.g.:

window['myVar'] = barcode.substr(0, 5)

To recall it inside other components, use the following syntax: {{ window['myVar'] }}.