Cannot access property via dot notation javascript -

this question has answer here:

• javascript property access: dot notation vs. brackets? 10 answers

var obj = {a:1,b:2}; var str = "a";  console.log(obj.str); 

this outputs undefined. missing here ?

you need use []

var obj = {a:1,b:2}; var str = "a";  console.log(obj[str]);