Differing JavaScript Support
IE doesn't support (most of) the extensions added to JavaScript since 1.5.
New in 1.6
- Array Methods -
indexOf(), lastIndexOf(), every(), filter(), forEach(), map(), some()
- for each ... in - iterates values instead of property names.
New in 1.7
- Destructuring assignment --
[a,b] = [1,2]
- Iterators and Generators
let and const statements- array comprehensions
New in 1.8
- Array Methods -
reduce(), reduceRight()
- Shortcuts for defining functions.
Some of these things require you to specify a version number of JavaScript to run under (which will break under IE), but some things like [1,2,3].indexOf(2) might not seem like that big a deal, until you try to run it in IE
