some helper function in nodejs

helper.ts

/**
     * Get random item in array
     *
     * @param {Object} array
     * @param {Number} n
     *
     * @return {Object}
     */
    random(array: any, n: number) {
        let result = new Array(n),
            len    = array.length,
            taken  = new Array(len);
        if (n > len)
            return array;

        while (n--) {
            let x     = Math.floor(Math.random() * len);
            result[n] = array[x in taken ? taken[x] : x];
            taken[x]  = --len in taken ? taken[len] : len;
        }

        return result;
    }

    /**
     * access object property with variable
     *
     * @param {Any}    obj
     * @param {String} prop
     *
     * @return Any
     */
    readProp(obj: any, prop: string) {
        return obj[prop];
    }

    /**
     * Get id from slug
     *
     * @param {string} slug
     *
     * @return {number}
     */
    getId(slug: string) {
        let arr: any = slug.split('-');
        let id: any  = arr.pop();
        id           = parseInt(id);

        return !lo.isNaN(id) ? id : 0;
    }

    /**
     * Round number
     *
     * @param {number} number
     * @param {number} decimals
     * @return {number}
     */
    round(number: number, decimals = 2) {
        return Number((number).toFixed(decimals));
    }

    /**
     * Convert string to slug
     *
     * @param {String} slug
     *
     * @return {String}
     */
    convertToSlug(slug: string) {
        //Change to lower case
        slug = slug.toLowerCase();
        //Remove vietnamese
        slug = slug.replace(/á|à|ả|ạ|ã|ă|ắ|ằ|ẳ|ẵ|ặ|â|ấ|ầ|ẩ|ẫ|ậ/gi, 'a');
        slug = slug.replace(/é|è|ẻ|ẽ|ẹ|ê|ế|ề|ể|ễ|ệ/gi, 'e');
        slug = slug.replace(/i|í|ì|ỉ|ĩ|ị/gi, 'i');
        slug = slug.replace(/ó|ò|ỏ|õ|ọ|ô|ố|ồ|ổ|ỗ|ộ|ơ|ớ|ờ|ở|ỡ|ợ/gi, 'o');
        slug = slug.replace(/ú|ù|ủ|ũ|ụ|ư|ứ|ừ|ử|ữ|ự/gi, 'u');
        slug = slug.replace(/ý|ỳ|ỷ|ỹ|ỵ/gi, 'y');
        slug = slug.replace(/đ/gi, 'd');
        //Remove special char
        slug = slug.replace(/\`|\~|\!|\@|\#|\||\$|\%|\^|\&|\*|\(|\)|\+|\=|\,|\.|\/|\?|\>|\<|\'|\"|\:|\;|_/gi, '');
        //Change space to '-'
        slug = slug.replace(/ /gi, "-");
        //Remove --
        slug = slug.replace(/\-\-\-\-\-/gi, '-');
        slug = slug.replace(/\-\-\-\-/gi, '-');
        slug = slug.replace(/\-\-\-/gi, '-');
        slug = slug.replace(/\-\-/gi, '-');
        slug = '@' + slug + '@';
        slug = slug.replace(/\@\-|\-\@|\@/gi, '');

        return slug;
    }

    /**
     * convert file to base64
     *
     * @param {string} file
     * @param {buffer}
     */
    async base64Encode(file: string) {
        let fs = require('fs');
        let bitmap = fs.readFileSync(file);

        return await new Buffer(bitmap).toString('base64');
    }

    /**
     * download file
     *
     * @param {string} url
     */
    async downloadImage(url: string) {
        const Fs = require('fs');
        const Path = require('path');
        const Axios = require('axios');
        const path = Path.resolve(__dirname, '../../../assets/images/downloads/', Path.basename(url))
        const writer = Fs.createWriteStream(path)

        const response = await Axios({
            url,
            method: 'GET',
            responseType: 'stream'
        })

        await response.data.pipe(writer)

        return await new Promise((resolve, reject) => {
            writer.on('finish', resolve)
            writer.on('error', reject)
        })
    }

    /**
     * convert file to base64 from url
     *
     * @param {string} url
     * @param {buffer}
     */
    async urlBase64Encode(url: string) {
        try {
            let axios = require('axios');
            let image = await axios.get(url, {responseType: 'arraybuffer'});

            return Buffer.from(image.data).toString('base64');
        } catch (ex) {
            return false;
        }
    }