JarCastingbreakable.js
Break out of functions, recursive or not, in a more composable way than by using exceptions explicitly. Non-local return.
Usage
You can use breakable to break out of simple loops like this example but note that it is often simpler to just use .some instead. Anyways, here's a minimal example.
var breakable = require("breakable");
breakable(function(brk) {
arr.forEach(function(v) {
if (...) {
brk();
}
});
});
Pass a value to brk and it becomes the return-value of breakable.
breakable is useful when you want to break out of a deep recursion, passing a value, without riddling your code with exception ceremony.
Instead of:
var esprima = require("esprima").parse;
var traverse = require("ast-traverse");
var ast = esprima("f(!x, y)");
var val;
try {
traverse(ast, {pre: function(node) {
if (node.type === "UnaryExpression" && node.operator === "!") {
val = node.argument;
throw 0;
}
}});
} catch(e) {
if (val === undefined) {
throw e; // re-throw if it wasn't our exception
}
}
console.dir(val); // { type: 'Identifier', name: 'x' }
you use breakable and do:
var breakable = require("breakable");
var esprima = require("esprima").parse;
var traverse = require("ast-traverse");
var ast = esprima("f(!x, y)");
var val = breakable(function(brk) {
traverse(ast, {pre: function(node) {
if (node.type === "UnaryExpression" && node.operator === "!") {
brk(node.argument);
}
}});
});
console.dir(val); // { type: 'Identifier', name: 'x' }
Installation
Node
Install using npm
npm install breakable
var breakable = require("breakable");
Browser
Clone the repo and include it in a script tag
git clone https://github.com/olov/breakable.git
<script src="breakable/breakable.js"></script>