JavaScript partially applied function - How to bind only the 2nd parameter?

Question

Sorry if I\'m missing something obvious, but I can\'t figure out how to bind a specific (nth) argument of a function in javascript. Most of my functional programming I\'ve

Answer 1

You can use lodash's _.bind to achieve this:

var add = function(a, b) {
  document.write(a + b);
};

// Bind to first parameter (Nothing special here)
var bound = _.bind(add, null, 3);
bound(4);
// → 7

// Bind to second parameter by skipping the first one with "_"
var bound = _.bind(add, null, _, 4);
bound(3);
// → 7

I am usually against libraries and prefer coding my own utility functions, but an exception can easily be made for lodash. I would highly suggest you check its documentation whenever you have a "This must be in the language somewhere!" moment. It fills in a lot of blanks in JavaScript.