Javascript arrow function examples

Arrow (=>) function expressions are shorter syntax compared to function expressions. Arrow functions are always anonymous. Here are some commonly used usage syntax patterns.

singleParam => expression
singleParam => { statements }
(param1, param2, …, paramN) => expression
(param1, param2, …, paramN) => { statements }

Assigning arrow function to a variable

var inc = x => x+1;
console.log("inc(3)= " + inc(3));

inc(3)= 4

arrow function to increment array values by 1

arr = [1, 3, 8];
newArr = arr.map(x => x+1);
console.log("newArr=" + newArr);

newArr=2,4,9

Same thing with slightly different syntax:

arr = [1, 3, 8];
newArr = arr.map(x => {console.log("x="+x); return x+1});
console.log("newArr=" + newArr);

x=1
x=3
x=8
newArr=2,4,9

arrow function with two args

Set array value as 0 if index is even.

arr = [1, 3, 8, 2, 5];
newArr = arr.map((x,i) => (i%2==0)? 0: x);
console.log("newArr=" + newArr);

newArr=0,3,0,2,0

Browser support

Note that Arrow function are not supported in IE.