Understanding the declaration of the underscore in _.js?
javascript, underscore.js
Solution
var _ = function(obj) {
// Either serve as the identity function on `_` instances,
// ... or instantiate a new `_` object for other input.
// If an `_` instance was passed, return it.
if (obj instanceof _) return obj;
// If someone called `_(...)`, rather than `new _(...)`,
// ... return `new _(...)` to instantiate an instance.
if (!(this instanceof _)) return new _(obj);
// If we are instantiating a new `_` object with an underlying,
// ... object, set that object to the `_wrapped` property.
this._wrapped = obj;
};
// If there is an exports value (for modularity)...
if (typeof exports !== 'undefined') {
// If we're in Node.js with module.exports...
if (typeof module !== 'undefined' && module.exports) {
// Set the export to `_`
exports = module.exports = _;
}
// Export `_` as `_`
exports._ = _;
} else {
// Otherwise, set `_` on the global object, as set at the beginning
// ... via `(function(){ var root = this; /* ... */ }())`
root._ = _;
}
Problem
This is from the beginning of the annotated source of _.js. Try though I may, my JavaScript abilities are not at a high enough level to understand what's going on here. I'm hoping someone can give a real step by step explanation. I really have literally no idea what the code below does besides somehow setting up the _ for use, despite that I understand each individual expression. ``` var _ = function(obj) { if (obj instanceof _) return obj; if (!(this instanceof _)) return new _(obj); this._wrapped = obj; }; if (typeof exports !== 'undefined') { if (typeof module !== 'undefined' && module.exports) { exports = module.exports = _; } exports._ = _; } else { root._ = _; } ```