4daf11528c
* Return inserted/replaced paths This gives `Path`’s replacement and insertion methods a consistent return value: the inserted/replaced paths. Before, they could return `undefined`, a `node`, or a the current path inside an array. It was kinda pointless. But now they always return an array of paths, which is useful for solving https://github.com/babel/babel/pull/4935#discussion_r96151368. * Return inserted nodes and not BlockStatement Addded test for bug #4363 * Cleanups - `#replaceWith` will now return the current path if it's the same node - `#insertAfter` and `#insertBefore` use public Path APIs now - Makes container insertion faster (single splice call) - Use public APIs in container insertion - Replacing a statement with an expression returns the expression's path - Replacing an expression with multiple statements returns the inserted closure's body's paths.
babel-plugin-transform-es2015-block-scoping
Compile ES2015 block scoping (const and let) to ES5
Examples
In
{
let a = 3
}
let a = 3
Out
{
var _a = 3;
}
var a = 3;
Installation
npm install --save-dev babel-plugin-transform-es2015-block-scoping
Usage
Via .babelrc (Recommended)
.babelrc
Without options:
{
"plugins": ["transform-es2015-block-scoping"]
}
With options:
{
"plugins": [
["transform-es2015-block-scoping", {
"throwIfClosureRequired": true
}]
]
}
Via CLI
babel --plugins transform-es2015-block-scoping script.js
Via Node API
require("babel-core").transform("code", {
plugins: ["transform-es2015-block-scoping"]
});
Options throwIfClosureRequired
In cases such as the following it's impossible to rewrite let/const without adding an additional function and closure while transforming:
for (let i = 0; i < 5; i++) {
setTimeout(() => console.log(i), 1);
}
In extremely performance-sensitive code, this can be undesirable. If "throwIfClosureRequired": true is set, Babel throws when transforming these patterns instead of automatically adding an additional function.