encodeBase64ToBase64Url

encodeBase64ToBase64Url Function

The encodeBase64ToBase64Url function transforms a standard Base64-encoded string into a Base64URL-safe format, which is commonly used in web tokens, URLs, and other contexts where Base64 characters (+, /, =) may be problematic.

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Purpose

Use this function when you need to:

• Convert a Base64-encoded value into a Base64URL-safe variant

• Ensure compatibility with URL-safe systems such as JWT (JSON Web Tokens)

• Pass encoded values in query strings or API endpoints

🔗 Specification: Base64URL Standard – base64.guru

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Function Definition

Property	Description
Function Name	this.encodeBase64ToBase64Url
Type	function
Available In	Server-Side Variables
Returns	string (Base64URL-encoded string)

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Parameters

Parameter	Description	Type	Required	Example
input	A valid Base64-encoded string	string		"YWJjKys="

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Conversion Behavior

This function applies the following transformations:

Base64 Character	Replaced With (Base64URL)
+	-
/	_
=	(removed)

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Example Usage

async function() {
    let x = this.encodeBase64ToBase64Url("YWJjKys="); // Base64 of "abc++"
    return x; // → "YWJjKys"
}

This converts the Base64 string "YWJjKys=" into a Base64URL-safe format by removing = padding and replacing special characters.

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Use Cases

• Encode payloads or claims for JWT (JSON Web Token)

• Safely pass encoded values in URLs or query parameters

• Normalize Base64 data for systems that reject or mishandle special characters

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Notes

• The input must be a valid Base64-encoded string. This function does not encode raw values — it only converts Base64 → Base64URL.

• For Base64 encoding of raw input, use native methods or pre-process before using this function.

• The resulting output will contain only URL-safe characters.

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Summary

this.encodeBase64ToBase64Url allows you to convert standard Base64 strings into the Base64URL format required by web standards like JWT. This ensures compatibility in environments where Base64 special characters can cause issues.