Function checkFileContent

src/main/electron.js:2666–2888

* Checks the file content type * Confirm content is xml, json, pdf, png, jpg, svg, vsdx ...

(body, enc)

 * Confirm content is xml, json, pdf, png, jpg, svg, vsdx ...
 */
function checkFileContent(body, enc)
{
	if (body != null)
	{
		let head, headBinay;
		
		if (typeof body === 'string')
		{
			if (enc === 'base64')
			{
				headBinay = Buffer.from(body.substring(0, 22), 'base64');
				head = headBinay.toString();
			}
			else
			{
				head = body.substring(0, 16);
				headBinay = Buffer.from(head);
			}
		}
		else
		{
			head = new TextDecoder("utf-8").decode(body.subarray(0, 16));
			headBinay = body;
		}
		
		let c1 = head[0],
		c2 = head[1],
		c3 = head[2],
		c4 = head[3],
		c5 = head[4],
		c6 = head[5],
		c7 = head[6],
		c8 = head[7],
		c9 = head[8],
		c10 = head[9],
		c11 = head[10],
		c12 = head[11],
		c13 = head[12],
		c14 = head[13],
		c15 = head[14],
		c16 = head[15];

		let cc1 = headBinay[0],
		cc2 = headBinay[1],
		cc3 = headBinay[2],
		cc4 = headBinay[3],
		cc5 = headBinay[4],
		cc6 = headBinay[5],
		cc7 = headBinay[6],
		cc8 = headBinay[7],
		cc9 = headBinay[8],
		cc10 = headBinay[9],
		cc11 = headBinay[10],
		cc12 = headBinay[11],
		cc13 = headBinay[12],
		cc14 = headBinay[13],
		cc15 = headBinay[14],
		cc16 = headBinay[15];