如何使用箭头功能

Question

I'm just reading up on ES6 features that have been implemented in Node v4.0.0 and saw Arrows. The example from Arrow Functions is:

var a = [
    "Hydrogen",
    "Helium",
    "Lithium",
    "Beryl­lium"
];
var a2 = a.map(function(s){ return s.length });
var a3 = a.map( s => s.length );

My question is how would I then use multiply lined code inside of a a.map( s => s.length ); Sometimes I need to play with things rather than just returning the length in this example.

I'm assuming its only used for returning the value and nothing else?

Answer 1

Just wrap your multiple code lines in curly braces like this:

var a3 = a.map( s => {
    var temp = s.length;
    return temp;
});