utils.js

'use strict';

function randomString(n) {
    let result = '';
    let alphabet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';

    let i = 0;
    while (i < n) {
        let index = Math.floor(Math.random() * alphabet.length);
        result += alphabet[index];
        i++;
    }

    return result;
}

function render(template, placeholders) {
    let result = template;
    for (let k in placeholders) {
        let regex = new RegExp('\\${' + k + '}', 'g');
        result = result.replace(regex, placeholders[k]);
    }
    return result;
}

function query(collection, condition) {
    let match = function (target, condition) {
        for (let key in condition) {
            if (target[key] != condition[key]) {
                return false;
            }
        }
        return true;
    };

    for (let i in collection) {
        if (match(collection[i], condition)) {
            return collection[i];
        }
    }

    return null;
}

module.exports = {
    randomString: randomString,
    render: render,
    query: query
};