Syntax error using => in IE

Question

I have the following line of javascript code

var res = Object.keys(packages).filter(e => packages[e] === true)

The above works well in all the other browser apart from IE. IE complains about Syntax erro at => can someone tell me how to get around this in IE

Unsupported syntax in IE - use a regular anonymous function: `.filter(function(e) {` — tymeJV, Jun 08 '17 at 13:47

Carcigenicate · Answer 1 · 2017-06-08T13:57:32.033

5

IE must not support arrow-functions. Just use the old function keyword.

.filter(function(e){ return packages[e] === true })

Side note, but you could also probably write this as:

.filter(function(e){ return packages[e] })

Unless packages[e] must actually be exactly equal to true and not just truthy.

edited Jun 08 '17 at 13:57

answered Jun 08 '17 at 13:48

Carcigenicate

https://caniuse.com/#feat=arrow-functions – Jonathan.Brink Jun 08 '17 at 13:49
The code example is wrong – Federico Galassi Jun 08 '17 at 13:51
@FedericoGalassi Which part? I freehanded it on my phone, so I may have introduced a syntax problem. – Carcigenicate Jun 08 '17 at 13:52
@FedericoGalassi Whoops, I forgot the `return`s. Fixed. – Carcigenicate Jun 08 '17 at 13:57

score 1 · Answer 2 · answered Jun 08 '17 at 13:49

1

IE doesn't support the fat arrow notation (Edge does). See http://kangax.github.io/compat-table/es6/. You need the older function notation:

var res = Object.keys(packages).filter(function(e) { return packages[e] === true })

answered Jun 08 '17 at 13:49

Federico Galassi

score 1 · Answer 3 · answered Jun 08 '17 at 13:50

1

CanIUse: Arrow function You cannot use it in IE;

var res = Object.keys(packages).filter(function(e) = {return packages[e] === true})

answered Jun 08 '17 at 13:50

Sebastian

3 Answers3