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

Since ES6 filter supports pointy arrow notation (like LINQ):

So it can be boiled down to following one-liner.

['a','b',1].filter(item => typeof item ==='string');