@extra-array/accumulate-update/index.js

Produces accumulating values.

'use strict';

/**
 * Produces accumulating values.
 * @param x an array (updated)
 * @param fr reduce function (acc, v, i, x)
 * @param acc initial value
 * @returns x
 */
function accumulate$(x, fr, acc) {
    var init = arguments.length <= 2;
    for (var i = 0, I = x.length; i < I; i++) {
        if (init) {
            acc = x[i];
            init = false;
        }
        else
            acc = fr(acc, x[i], i, x);
        x[i] = acc;
    }
    return x;
}

module.exports = accumulate$;