Enhanced Javascript
bind()
function.
Because the [[BoundThis]]
internal properties of a bound function are not programmatically accessible, and you might need to get the context of a function without executing it. This lib also provides some tooling around the bind
mechanism.
npm install bind2
bind
API.bind2()
) :
unbind()
(Function). Will return the original unbound function.unbound
(Function). Reference to the original unbound function.context
(Any). Get the function context without executing it.bound
(Boolean). Returns true
if the function has been bound with bind2
.bind2(context, ...parameters)
(Function). Re-bind the function. (Note : bind()
still exists.)
const bind2 = require('bind2');
function test() {
return this.hello;
}
const context = { hello: 'world' };
// Native `bind()`.
const boundFn = test.bind(context);
console.log(boundFn.context); // undefined
console.log(boundFn.bound); // undefined
console.log(bound2Fn.unbound); // undefined
console.log(bound2Fn.unbind()); // TypeError: bound2Fn.unbind is not a function
console.log(boundFn()); // 'world'
// `bind2()`.
const bound2Fn = bind2(test, context);
console.log(bound2Fn.context); // { hello: 'world' }
console.log(bound2Fn.bound); // true
console.log(bound2Fn.unbound); // [Function: test]
console.log(bound2Fn.unbind()); // [Function: test]
console.log(bound2Fn()); // 'world'
const bind2 = require('bind2');
bind2(fn, thisArg[, arg1[, arg2[, ...]]])
This function is a wrapper of the native bind()
function.
Arguments :
fn
(Function) : the function to bind.thisArg
: the value to be passed as the this
parameter to the target function when the bound function is called. The value is ignored if the bound function is constructed using the new
operator. When using bind
to create a function (supplied as a callback) inside a setTimeout
, any primitive value passed as thisArg
is converted to object. If no arguments are provided to bind
, the this
of the executing scope is treated as the thisArg
for the new function.arg1, arg2, ...
: arguments to prepend to arguments provided to the bound function when invoking the target function.Returns : a copy of the given function with the specified this value and initial arguments.
bind2.fn(fn, thisArg[, arg1[, arg2[, ...]]])
Alias to bind2(fn, thisArg[, arg1[, arg2[, ...]]])
.
bind2.define()
Alias to bind2.wrap(Function.prototype)
.
This will mutate the Function
's prototype, thus adding the bind2()
and bound
properties to every function. It is recommended to execute this once, in the beginning of the script.
e.g.:
const bind2 = require('bind2');
// Wrap `Function.prototype`.
bind2.define();
function test() {
return this.hello;
}
const context = { hello: 'world' };
// Use the new `bind2()` function.
const boundFn = test.bind2(context);
console.log(boundFn.context); // { hello: 'world' }
MIT