javascript - How to add items to array in nodejs

Question

How do I iterate through an existing array and add the items to a new array.

var array = [];
forEach( calendars, function (item, index) {
    array[] = item.id
}, done );

function done(){
   console.log(array);
}

The above code would normally work in JS, not sure about the alternative in node js. I tried .push and .splice but neither worked.

Answer 1

Check out Javascript's Array API for details on the exact syntax for Array methods. Modifying your code to use the correct syntax would be:

var array = [];
calendars.forEach(function(item) {
    array.push(item.id);
});

console.log(array);

You can also use the map() method to generate an Array filled with the results of calling the specified function on each element. Something like:

var array = calendars.map(function(item) {
    return item.id;
});

console.log(array);

And, since ECMAScript 2015 has been released, you may start seeing examples using let or const instead of var and the => syntax for creating functions. The following is equivalent to the previous example (except it may not be supported in older node versions):

let array = calendars.map(item => item.id);
console.log(array);