javascript - Function doesn't return true -

this question has answer here:

• how return response asynchronous call? 21 answers

why never true returned? given name exists in array rows , if(rows[i].username == name) gets triggert, why won't function return true?

function existuser(name){     var result = false;     ootw.mysql.query('select * time',function(err,rows){     if(err) throw err;         (var = 0; < rows.length; i++) {              if (rows[i].username == name) {                  result = true;              }         };       });     console.log(result);     return result; } 

your query executes asynchronously, long after result returned.