Syntax error using => in IE [duplicate]

问题

This question already has answers here:

Syntax error in IE using ES6 arrow functions (2 answers)

Closed 3 years ago.

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

回答1:

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.

回答2:

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 })

回答3:

CanIUse: Arrow function You cannot use it in IE;

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

来源：https://stackoverflow.com/questions/44437497/syntax-error-using-in-ie