how-to-access-object-properties.md

var obj = {

"name" : "Saif",
"username" : "saifsmailbox98"

}; //object

var name = "username";  //variable name contains a string "username"

obj.name; // "Saif"
obj["name"]; // "Saif"
obj[name]; // "saifsmailbox98"
obj.username; // "saifsmailbox98"
obj["username"]; // "saifsmailbox98"
obj[username]; // ReferenceError: username is not defined 

1. looks for the property named name and returns it's value (variable name not used here).
2. same as above.
3. looks for the property that the variable name contains that is "username" (variable name used here).
4. looks for the property named username and returns it's value (variable name not used here).
5. same as above.
6. looks for the property that the variable username contains (variable username does not exist).

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