I got asked this in an Interview and I couldn't solve it. Was wondering if any of you guys can help me.

fn("hello").fn("world").fn("!!!").fn();

function fn (str){
  // Enter Solution Here
}

The solution should return 'hello world !!!'.

I tried method chaining and was able to get a partially right answer which is as follows:

function fn(str) {
    var string = str;
    this.fn1 = function(str1) {
        string  = " " str1;
        return this;
    }
    this.fn = function() {
        console.log(string)
    }
}

new fn("hello").fn1("world").fn1("!!!").fn();

but as you can see I cant get it to work unless I use fn1 as the function to concat the string. Any help will be appreciated, thanks.

CodePudding user response：

Have the function return an object with one fn method. If, when you call it, it has an argument, update the string, otherwise return the string so you can log it.

function fn(str = '') {
  return {
    fn: function (s) {
      if (s) {
        str  = ` ${s}`;
        return this;
      }
      return str;
    }
  };
}

const output = fn('hello').fn('world').fn('!!!').fn();
console.log(output);

Additional documentation

• Template/string literals

CodePudding user response：

You could return an object with two properties, one for returning the complete string and another for collecting parts and retuning the object.

function fn(str) {
    const
        fns = {
            fn: function () {
                return str;
            },
            fn1: function (s) {
                str  = ' '   s;
                return fns;
            }
        };
    return fns;
}

console.log(fn("hello").fn1("world").fn1("!!!").fn());

CodePudding user response：

I think this should do the trick:

function fn(s){
  return new function(){
     this.str = s;
     this.fn = (ns) => {if(ns){this.str  = " " ns; return this;} else return this.str;};
  }
}


let a = fn("hello").fn("world").fn("!!!").fn(); 
console.log(a);

CodePudding user response：

Seems like you need to use objects

const generic = {
    "fn1":null,
    "current":"",
    "fn": () => {
     //what do you want to do with "this.current"?
    }

}
function fn(str) {
    var ret = generic;
    ret.fn1 = (wa) =>{
        var again = generic;
        again.current  =wa;
        return again;
    }
    ret.current  = str;
    return ret;
}