51 lines
1.2 KiB
Markdown
51 lines
1.2 KiB
Markdown
---
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title: Bind specific arguments of a function
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date: 2019-03-08 09:00:00
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tags:
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- JavaScript
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category: tech
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keywords:
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- Javascript
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- ES2015
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- ES6
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---
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To bind specific (nth) arguments of a function, we can write a decorator instead of using `Function.bind()`:
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```js
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function func(p1, p2, p3) {
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console.log(p1, p2, p3);
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}
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// the binding starts after however many are passed in.
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function decorator(...bound_args) {
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return function(...args) {
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return func(...args, ...bound_args);
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};
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}
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// bind the last parameter
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let f = decorator("3");
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f("a", "b"); // a b 3
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// bind the last two parameter
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let f2 = decorator("2", "3")
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f2("a"); // a 2 3
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```
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Even if we want to bind just the nth argument, we can do as follows:
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```js
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// bind a specific (nth) argument
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function decoratorN(n, bound_arg) {
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return function(...args) {
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args[n-1] = bound_arg;
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return func(...args);
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}
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}
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let fN = decoratorN(2, "2");
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fN("a","b","c"); // a 2 c
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```
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[https://stackoverflow.com/questions/27699493/javascript-partially-applied-function-how-to-bind-only-the-2nd-parameter](https://stackoverflow.com/questions/27699493/javascript-partially-applied-function-how-to-bind-only-the-2nd-parameter)
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