Sort an array without using in build functions

Code to sort the given array without using Inbuilt functions

sortarray.js

@@ -0,0 +1,11 @@
+var a=[1,3,2,7,4,10,9];
+for(var i=0;i<a.length;i++){
+   var a1=a[i];
+   var a2=a[i+1];
+   var dif = a1-a2;
+   if(dif>0){
+    a[i]=a[i+1];
+    a[i+1]=a1;
+   }
+}
+console.log(a);