How can I encode a file into a base 64?

[OhmsG]

Using js I need to create a script that converts a local file into a base 64 string.  Any ideas how I can achieve this?

I saw a post from about 8 years ago, outdated and it said:  

var file = newFile(filePath);
file.encoding = 'BINARY';

However looking through js Illustrator documentation I don't find a method for encoding.

[Ten A]

You need to encode yourself.

Here is a sample function you can reference.

function base64(fileNm) {
	var startDate = new Date();
	$.writeln("Base64 encode start time= " + startDate);
	var theFile = new File(fileNm);
	theFile.encoding = "binary";
	theFile.open("r");
	var binStr = theFile.read();
	theFile.close();
	var flNm = "/tmpfile.txt";
	var tmpFile = new File(flNm);
	tmpFile.open("w");	
	szB64 = new Array;
	var keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";	// Accepted b64 chars
	for (j=0;j<64;j++){
		szB64[j] = keyStr.charAt(j);
		}
	var ecdStr = "";
	var counter = 0;
	var binLen = binStr.length - (binStr.length % 3); 
	for (i=0;i<binLen;i+=3) {		// Get 3 chars starting at the begining of the binary string
		ecdStr += szB64[binStr.charCodeAt (i) >> 2];
		ecdStr += szB64[((binStr.charCodeAt (i) & 0x3) << 4) | (binStr.charCodeAt (i+1) >> 4)];
		ecdStr += szB64[((binStr.charCodeAt (i+1) & 15) << 2) | (binStr.charCodeAt (i+2) >> 6)];
		ecdStr += szB64[binStr.charCodeAt (i+2) & 0x3f];
		counter +=4;
		if(counter > 75) {		// when hit the limit, write the line and reset counter
			tmpFile.writeln (ecdStr);
			ecdStr = "";
			counter = 0;
			}
		}

	switch (binStr.length % 3){
		case 2: //padding 1 characters.
			ecdStr += szB64[binStr.charCodeAt (i) >> 2];
			ecdStr += szB64[((binStr.charCodeAt (i) & 0x3) << 4) | (binStr.charCodeAt (i+1) >> 4)];
			ecdStr += szB64[((binStr.charCodeAt (i+1) & 15) << 2) | (binStr.charCodeAt (i+2) >> 6)];
			ecdStr += "=";
			tmpFile.writeln (ecdStr);	
		break;
		case 1: //padding 2 character.
			ecdStr += szB64[binStr.charCodeAt (i) >> 2];
			ecdStr += szB64[((binStr.charCodeAt (i) & 0x3) << 4) | (binStr.charCodeAt (i+1) >> 4)];
			ecdStr += "=="
			tmpFile.writeln (ecdStr);	
		break;
		default:
			tmpFile.writeln (ecdStr);	
		break;
		}
	tmpFile.close();
	var endDate = new Date();
	$.writeln("Base64 encode finish time = " + endDate);
	}

[OhmsG]

@Ten A 

I'm getting the file path like this:

function uploadImage() {
var f = window.cep.fs.showOpenDialog(false, false, "select jpg file...", "", ["jpg"]);
base64(f.data);
}

But I get no response or error.  Is the path and file name what I should pass?

[Ten A · Accepted solution]

Previous one is ExtendScript function.

In case of CEP, You can use encodin conversion utils.

var result = window.cep.fs.readFile("~/Desktop/testFilepath.jpg");

if (0 == result.err) {

var binDat = result.data;

var data = cep.encoding.convertion.binary_to_b64(binDat); 
console.log(data);

}