Browser support

[Rich-Harris]

A few people have asked about browser support. We probably should be able to answer the question conclusively (maybe even running some tests in Browserstack or whatever?), and perhaps tell people which polyfills they'll need.

For example, window.performance.now isn't supported in IE9, but is used in transitions (#525 (comment)).

[kaisermann]

It also doesn't (completely) work in Safari 5.1: the querySelector(':checked') always returns []

[arxpoetica]

I marked this as a v1 Q, but it's also relevant to v2-- I think it's just a matter of documenting the expectations. Is this documented somewhere other than the blog post, or is that sufficient enough?

[jihchi]

Also, Object.create isn't supported in IE8

[JohnRiv]

The lack of some sort of official browser support matrix is what is preventing me from being able to use Svelte at work. IE11 & Safari 10 support is what I'm particularly interested in, although others may need support for older versions of those browsers as well.

[JohnRiv]

I haven't had a chance to try out this ESLint plugin yet, but I wonder if this will answer our question: https://github.com/instea/eslint-plugin-builtin-compat

[kaisermann]

@JohnRiv If you want to use v2.0.0+, the ES5 constraint was dropped (#1359). I'm currently using it in a very old webkit environment by polyfilling it with @babel/preset-env and it's working fine (for now).

[mblarsen]

IE11 const in for not supported

svelte/src/internal/utils.js

Line 6 in ce9eba8

for (const k in src) tar[k] = src[k];