Is map() in javascript synchronous?
asynchronous, dictionary, javascript, synchronous
Solution
Yes, map is synchronous. It's a higher order function, that takes a new function and applies it to the given array.
Some people think that because they give a function as a parameter to `map` then it 'should' act like an event callback function, but it really doesn't. The `map` function just applies the function parameter to the array and only after it finishes, it continues execution for the resulting code after the map block.
As to your 'expected behavior' - it just doesn't work like you think ;)
Problem
Function is : ``` [1,2,3].map( function (item) { console.log(item); //return 'something'; }); ``` My expected behaviour is getting only 1 as output, unless i uncomment the ``` //return 'something' ``` But i really get ``` 1 2 3 ``` What am i doing wrong ? UPDATE: i am testing that with nodejs. i really dont understand. ``` var async = require("async"); [1,2,3].map( function (item) { console.log(item); //return 'something'; }); async.map([1,2,3], function (item,callback) { console.log(item); //callback(null,true) }, function (err,result) { console.log(result); } ); ``` Both return the same ``` 1 2 3 ``` And i really would like to wait till i get a return or a callback till the next item is executed. SOLVED ``` async.mapSeries([1,2,3], function (item,callback) { console.log(item); //callback(null,true) }, function (err,result) { console.log(result); } ); ``` is the way to do it.