check if some source code uses syntax supported by an ES version
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check if some source code uses syntax supported by an ES version
You can use this before eg. running Babel with a million transforms on a file. Note that this attempts to parse the file using acorn, so it is pretty slow; recommended to memoize the result!
npm install is-es-version
var isEsVersion = require('is-es-version')
isEsVersion('const a = 10', 5) // false
isEsVersion('var a = 10', 5) // true
isEsVersion(src, version=5, opts={})
Check if src
is a source code string that is supported by the EcmaScript version version
. The default version is 5. Returns true if the syntax is supported by the given version; false if not.
Set opts.parser
to use a custom parser module, such as acorn-node.
isEsVersion('#!/usr/bin/env node\nrequire("./lib/cli")', 5, { parser: require('acorn-node') })