regex - RexExp in javascript dont match a number inside a string -

im learning regular expresions in javascript , there thing dont understand.

the following regexp should match string z if add number says correct

var patron = /[a-za-z]/; var regex = new regexp(patron);         var v= "hello word 512";          if(v.match(regex))         {             //should not match         }else         {             objinput.style.color = "red";         } 

and them tried this:

 var patron = /[a-za-z\d]/; var regex = new regexp(patron);         var v= "hello word 512";          if(v.match(regex))         {             //should not match still dont work         }else         {             objinput.style.color = "red";         } 

and also, parentheses not being match

 var patron = /[a-za-z\"\']/;     var regex = new regexp(patron);             var v= "hello word 512";          if(v.match(regex))         {             //it match whenever double quoute followed single quoute'         }else         {             objinput.style.color = "red";         } 

about first example provided, regex /[a-za-z]/ checks character in input string. since finds h in input string, returns true. need place start , end anchors, ^ , $ in regex. new regex this:

/^[a-za-z]+$/ 

you can make changes regex accordingly.
match parentheses, need escape them backslash. \( match (, , \) match ).