Bind specific arguments of a function

1 minute read

To bind specific (nth) arguments of a function, we can write a decorator instead of using Function.bind():

 1function func(p1, p2, p3) {
 2    console.log(p1, p2, p3);
 3}
 4// the binding starts after however many are passed in.
 5function decorator(...bound_args) {
 6    return function(...args) {
 7        return func(...args, ...bound_args);
 8    };
 9}
10
11// bind the last parameter
12let f = decorator("3");
13f("a", "b");  // a b 3
14
15// bind the last two parameter
16let f2 = decorator("2", "3")
17f2("a");  // a 2 3

Even if we want to bind just the nth argument, we can do as follows:

 1// bind a specific (nth) argument
 2function decoratorN(n, bound_arg) {
 3    return function(...args) {
 4        args[n-1] = bound_arg;
 5        return func(...args);
 6    }
 7}
 8
 9let fN = decoratorN(2, "2");
10fN("a","b","c"); // a 2 c

https://stackoverflow.com/questions/27699493/javascript-partially-applied-function-how-to-bind-only-the-2nd-parameter

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