encodeBase64UrlToBase64

encodeBase64UrlToBase64 Function

The encodeBase64UrlToBase64 function converts a Base64URL-encoded string back into a standard Base64 format. This is useful for decoding or interoperability with systems that expect standard Base64 syntax.

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Purpose

Use this function when you need to:

• Convert a Base64URL-safe string into a valid Base64 string

• Decode values originally encoded in Base64URL (e.g., JWT segments)

• Restore compatibility with tools or APIs that do not accept Base64URL

🔗 Specification: Base64URL Standard – base64.guru

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Function Definition

Property	Description
Function Name	this.encodeBase64UrlToBase64
Type	function
Available In	Server-Side Variables
Returns	string (Base64-standard encoded output)

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Parameters

Parameter	Description	Type	Required	Example
input	A valid Base64URL-encoded string	string		"YWJjKys"

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Conversion Behavior

This function performs the following transformations:

Base64URL Character	Replaced With (Base64)
-	+
_	/
(padding)	Adds = to match Base64 length (if needed)

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Example Usage

async function() {
    let x = this.encodeBase64UrlToBase64("YWJjKys"); // Base64URL of "abc++"
    return x; // → "YWJjKys="
}

This example converts a Base64URL-safe string into a valid Base64 string by restoring special characters and padding.

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Use Cases

• Decode JWT payloads or headers encoded in Base64URL

• Restore encoded values for Base64-compatible APIs

• Ensure data consistency across encoding formats

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Notes

• The input must be a valid Base64URL string.

• This function does not decode the value — it only reformats Base64URL to Base64. Use decoding functions separately if needed.

• Automatically restores padding (=) when missing.

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Summary

this.encodeBase64UrlToBase64 enables seamless transformation of Base64URL-safe strings into standard Base64 format. It ensures compatibility with systems expecting strict Base64 syntax, making it essential for working with JWTs, APIs, or external integrations in JENTIS.