Why does javascript map function return undefined?

Question

My code

 var arr = [\'a\',\'b\',1];
 var results = arr.map(function(item){
                if(typeof item ===\'string\'){return item;}  
               });
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Answer 1

var arr = ['a','b',1];
 var results = arr.filter(function(item){
                if(typeof item ==='string'){return item;}  
               });