Collection

Collection manipulation functions

forEach or each

Iterate through all elements of a collection

const obj = { a: '1', b: '2', c: '3' };
_.forEach(obj, (value, key) => {
    console.log(value, key);
});
// a1, b2, c3


const arr = ['a', 'b', 'c'];
_.each(arr, (value, key) => {
    console.log(value, key);
});
// 0a, 1b, 3c

map

Create a new array with a collection as base

const arr = [1, 2, 3, 4];
const m = _.map(arr, (value, key) => {
    return `${key}:${value}`;
});
// m is ['0:1', '1:2', '2:3', '3:4']

const obj = { a: 1, b: 2, c: 3 };
const om = _.map(arr, (value, key) => {
    return `${key}:${value}`;
});
// om is ['a:1', 'b:2', 'c:3']

filter

Filter a collection

• filter (arr{array}, iteratee{function}): {array}
• iteratee{function} (currentItem{any}, key{string|number}, collection{array|object}) : {bool}

const arr = [
    { id: 1, name: 'Fabio' },
    { id: 2, name: 'Ingrid' },
    { id: 3, name: 'Eddy' },
];

const result = _.filter(arr, item => item.id === 1);

// result is [{ id:1, name: 'Fabio'}]