javascript - Default Parameters in Function Expressions -

default parameters in javscript function declerations can achieved simple assignment follows:

function foo(arg1 = 'default1', arg2 = 'default2') { ... } 

but how can have default parameters function expressions, following not work in chrome v47:

var foo = function (arg1 = 'default1', arg2 = 'default2') { ... } 

any pointers helpful.

you can't in javascript:

function foo(arg1 = 'default1', arg2 = 'default2') { ; } 

see in console, gives syntax error. can this:

function foo(arg1, arg2) {    if ("undefined" == typeof arg2) {        arg2 = "default2";    } }  var foo2 = function(arg1, arg2) {    if ("undefined" == typeof arg2) {        arg2 = "default2";    } }