Detailed explanation of the idea code for obtaining the barcode scanned by scanning the code gun using JavaScript.

 var keycode = "";
  var lastTime=null,nextTime;
  var lastCode=null,nextCode;
	document.οnkeydοwn=function(e){
		if(){
			// IE
			nextCode = 
		} else if(){
			// Netscape/Firefox/Opera
			nextCode = 
		}
		
		//+ key, add new data row		if(nextCode==107 || nextCode==187){
			addNewGoodLine();
		} 
		//-key, delete the last line of data		else if(nextCode==109 || nextCode==189){
			$(".new_products:last").remove();
		}
		//The number keys above the letters 0-9 correspond to the key code value 48-57		//Number keypad Number key 0-9 corresponding key code value 96-105		else if((nextCode>=48&&nextCode<=57) || (nextCode>=96&&nextCode<=105)){
			//There is a problem with the corresponding characters of the keycode value of the numeric keyboard, so manually adjust the keycode value.			var codes = {'48':48,'49':49,'50':50,'51':51,'52':52,'53':53,'54':54,'55':55,'56':56,'57':57,
						 '96':48,'97':49,'98':50,'99':51,'100':52,'101':53,'102':54,'103':55,'104':56,'105':57
			};
			nextCode = codes[nextCode];
			nextTime = new Date().getTime();
		  if(lastCode == null && lastTime == null) {
		  	keycode = (nextCode);
		  } else if(lastCode != null && lastTime != null && nextTime - lastTime <= 30) {
		  	keycode += (nextCode);
		  } else{
				keycode = "";
			  lastCode = null;
			  lastTime = null;
			}
		  lastCode = nextCode;
		  lastTime = nextTime;
		}
		//13 is the key Enter		else if(nextCode==13 && keycode!= ""){
			var code = $(".new_products:last .code").val();
			if(code != ""){
				//The last line has entered data, and a new line is regenerated				addNewGoodLine();
			}
			$(".new_products:last .code").val(keycode).blur();
			keycode = "";
		  lastCode = null;
		  lastTime = null;
		}
	}
	
	function addNewGoodLine(){
		//Generate new data row		var html = '<tr class="new_products">';
			html += '	<td></td>';
			html += '	<td>';
			html += '		<input type="text" class="code" οnblur="getProductDetail()" />';
			html += '	</td>';
			html += '</tr>';
	}
	
	function getProductDetail(){
		//Get the product details and assign the value		
	}