bad lodash iterations

test.js

const _ = require('lodash');

const hasLength = {
    length: 4,
    a: 1,
    b: 2,
};

const normal = {
    a: 1,
    b: 2,
};

function print(tag) {
    return (v, k) => console.log(`[${tag}] val=${v}, key=${k}`);
}

['each', 'map', 'every', 'filter', 'values'].forEach((method) => {
    _[method](hasLength, print(`${method} - hasLength`));
    _[method](normal, print(`${method} - normal`));
});

// It will print:
// [each - hasLength] val=undefined, key=0
// [each - hasLength] val=undefined, key=1
// [each - hasLength] val=undefined, key=2
// [each - hasLength] val=undefined, key=3
// [each - normal] val=1, key=a
// [each - normal] val=2, key=b
// [map - hasLength] val=undefined, key=0
// [map - hasLength] val=undefined, key=1
// [map - hasLength] val=undefined, key=2
// [map - hasLength] val=undefined, key=3
// [map - normal] val=1, key=a
// [map - normal] val=2, key=b
// [every - hasLength] val=undefined, key=0
// [every - normal] val=1, key=a
// [filter - hasLength] val=undefined, key=0
// [filter - hasLength] val=undefined, key=1
// [filter - hasLength] val=undefined, key=2
// [filter - hasLength] val=undefined, key=3
// [filter - normal] val=1, key=a
// [filter - normal] val=2, key=b