Matching of two strings in JavaScript

There was a problem in the work, two strings matched, which requires that each string contain at most one *, ?Can be infinite

* stands for a string of any length, ?Represents a character

Request can suggest two conflicts

<input type="text" id="str1"><br>

<input type="text" id="str2"><br>

<input type="button" onclick="checkMarchX()" value="CHECK">

The code implemented with JavaScript is as follows:

function checkMarchX()
{
	var str1 = document.getElementById('str1').value;
	var str2 = document.getElementById('str2').value;
	var str1XPosition = str1.indexOf('*');
	var str2XPosition = str2.indexOf('*');
	if(str1XPosition!=-1 && str2XPosition!=-1)// Both contain *
	{
		var position = str1XPosition>str2XPosition?str2XPosition:str1XPosition;//success
		if(position!=0)
		{
			var patbeforeStr1 = str1.substring(0,position);
			var patbeforeStr2 = str2.substring(0,position);
			if(checkMarchQ(patbeforeStr1,patbeforeStr2))
			{
				//alert(str1+' and '+str2+" First half conflict ");
				// Then test the second half 
				var str1XBackPosition = str1.length-str1XPosition-1;
				var str2XBackPosition = str2.length-str2XPosition-1;
				var backposition = str1XBackPosition>str2XBackPosition?str2XBackPosition:str1XBackPosition;
				if (backposition==0)
				{
					alert(str1+' and '+str2+" conflict ");
				}
				else
				{
					var patbackStr1 = str1.substring(str1.length-backposition,str1.length);
					var patbackStr2 = str2.substring(str2.length-backposition,str2.length);
					if(checkMarchQ(patbackStr1,patbackStr2))
					{
						alert(str1+' and '+str2+" conflict ");
					}
				}
			}
		}
		else
		{
			//alert(str1+' and '+str2+" First half conflict ");
			var str1XBackPosition = str1.length-str1XPosition-1;
			var str2XBackPosition = str2.length-str2XPosition-1;
			var backposition = str1XBackPosition>str2XBackPosition?str2XBackPosition:str1XBackPosition;
			if (backposition==0)
			{
				alert(str1+' and '+str2+" conflict ");
			}
			else
			{
				var patbackStr1 = str1.substring(str1.length-backposition,str1.length);
				var patbackStr2 = str2.substring(str2.length-backposition,str2.length);
				if(checkMarchQ(patbackStr1,patbackStr2))
				{
					alert(str1+' and '+str2+" conflict ");
				}
			}
		}
	}
	else if((str1XPosition==-1 && str2XPosition!=-1)||(str1XPosition!=-1 && str2XPosition==-1))// Yes and only 1 String contains *
	{
		var strX = str1XPosition==-1?str2:str1;// Contain * String of 
		var strNoX = str1XPosition==-1?str1:str2;// Does not contain * String of 
		if (strX.length-1<strNoX.length)
		{
			var position = strX.indexOf('*');
			if(position==0)
			{
				//alert(str1+' and '+str2+" First half conflict ");
				var backposition = strX.length-position-1;
				if (backposition==0)
				{
					alert(str1+' and '+str2+" conflict ");
				}
				else
				{
					var patbackStr1 = str1.substring(str1.length-backposition,str1.length);
					var patbackStr2 = str2.substring(str2.length-backposition,str2.length);
					if(checkMarchQ(patbackStr1,patbackStr2))
					{
						alert(str1+' and '+str2+" conflict ");
					}
				}
			}
			else
			{
				var patbeforeStr1 = str1.substring(0,position);
				var patbeforeStr2 = str2.substring(0,position);
				if(checkMarchQ(patbeforeStr1,patbeforeStr2))
				{
					//alert(str1+' and '+str2+" First half conflict ");
					var backposition = strX.length-position-1;
					if (backposition==0)
					{
						alert(str1+' and '+str2+" conflict ");
					}
					else
					{
						var patbackStr1 = str1.substring(str1.length-backposition,str1.length);
						var patbackStr2 = str2.substring(str2.length-backposition,str2.length);
						if(checkMarchQ(patbackStr1,patbackStr2))
						{
							alert(str1+' and '+str2+" conflict ");
						}
					}
				}
			}
		}
	}
	else
	{
		if(checkMarchQ(str1,str2))
		{
			alert(str1+' and '+str2+" conflict ");
		}
	}
}
function checkMarchQ(str1,str2)
{
	var flagque = false;
	if(str1.length==str2.length)
	{
	  // Conflict is possible only if the length is the same 
		for (var i=0 ;i<str1.length ;i++ )
		{
			if(str1.substr(i,1)!='?' && str2.substr(i,1)!='?')
			{
				if(str1.substr(i,1)!=str2.substr(i,1))
				{
					flagque = false;// Indicates no conflict 
					break;
				}
				else
				{
					flagque = true;// Represent Conflict 
				}
			}
		}
	}
	return flagque;
}

The above program does not validate the validity of the input.