How to re-bind() the same function in Javascript?

Question

I am writing a wrapper that accepts a callback function to pass on to another function or execute directly. The problem is that another functions have bound parameters with callback parameter having a different argument number. Therefore initial binding would accept a string placeholder that needs to be replaced. But how?

function callback(){}

function asyncfunc1(a,b,callback,d){ callback();}
function asyncfunc2(a,b,c,callback){ callback();}
function asyncfunc3(callback,b,c,d){ callback();}

function wrap(cond,func,callback){
    if  (cond) {
        // here I want to execute the passed function
        // however instead of real callback, I have a placeholder bound
        // so how do I bind it again to replace it with real callback?
        func(); 
    }
    else callback();
}

wrap(cond,asyncfunc1.bind(null,param1,param2,'callback',param3),callback)

// this is what it's used for, is to create a flow of conditional callbacks

wrap(cond1,asyncfunc1.bind(null,param1,param2,'callback',param4),function(){
    wrap(cond2,asyncfunc2.bind(null,param1,param2,param3,'callback'),function(){
        wrap(cond3,asyncfunc3.bind(null,'callback',param2,param3,param4),callback
    }
})

You want partial application but with a different "open slot" every time? So, you can partially apply, say, parameters 1, 3, and 4 and leave 2 for later? — VLAZ, Jun 22 '20 at 07:05
I want to use nested anonymous function callbacks, which I can only pass once so I have to replace the other one inside the wrapper. — Anonymous, Jun 22 '20 at 07:09

score 0 · Accepted Answer · answered Jun 22 '20 at 09:58

I am going to avoid bind and pass a function with arguments as an array.

function wrap(cond,fn_arr,callback){
    if  (cond) {
        if (fn_arr instanceof Array){
            var func=fn_arr.shift();
            if (fn_arr.includes('callback')) {
                fn_arr[fn_arr.indexOf('callback')] = callback;
            }
            func(...fn_arr)
        } else fn_arr();
    }
    else callack();
}

Then with little array manipulation will do the replacement trick.

wrap(cond,[asyncfunc,param1,param2,'callback',param4],callback)

How to re-bind() the same function in Javascript?

1 Answers1