Javascript Connection

Connection.js

//import React from 'react';

const timeout = 5000;

const Connection = {
    isObject: function (v) {
        while (Object.prototype.toString.call(v) === '[object Object]') {
            if ((v = Object.getPrototypeOf(v)) === null) {
                return true;
            }
        }
        return false;
    },
    fetchWrapper: function (url, options) {
        return new Promise((resolve, reject) => {
            fetch(url, options).then(resolve, reject);
            if (options && options?.timeout) {
                const e = new Error('Connection timed out');
                setTimeout(reject, options?.timeout, e);
            }
        });
    },
    get: function (url, config) {
        let then1 = {};
        const defaultInit = {
            method: 'GET',
            timeout: timeout,
        };
        const init = Object.assign({}, defaultInit, config);

        return new Promise((resolve, reject) => {
            this.fetchWrapper(url, init).then((response) => {
                then1 = response;
                if (response.headers.get('content-type') && response.headers.get('content-type').match(/application\/json/)) {
                    return response.json();
                }
                return response;
            }).then(res2 => {
                const then2 = {data: res2};
                const result = Object.assign({}, then2, then1, {config: init});
                if (then1.ok) {
                    resolve(result);
                } else {
                    reject(result);
                }
            }).catch(err => reject(err));
        });
    },
    post: function (url, data, config) {
        const isData = typeof data;
        const body = isData === 'object' ? JSON.stringify(data) : data;
        let then1 = {};
        const defaultInit = {
            method: 'POST',
            body: body,
            timeout: timeout,
        };
        const init = Object.assign({}, defaultInit, config);

        return new Promise((resolve, reject) => {
            this.fetchWrapper(url, init).then((response) => {
                then1 = response;
                if (response.headers.get('content-type') && response.headers.get('content-type').match(/application\/json/)) {
                    return response.json();
                }
                return response;
            }).then(res2 => {
                const then2 = {data: res2};
                const result = Object.assign({}, then2, then1, {config: init});
                if (then1.ok) {
                    resolve(result);
                } else {
                    reject(result);
                }

            }).catch(err => reject(err));
        });
    },
    put: function (url, data, config) {
        const isData = typeof data;
        const body = isData === 'object' ? JSON.stringify(data) : data;
        let then1 = {};
        const defaultInit = {
            method: 'PUT',
            body: body,
            timeout: timeout,
        };
        const init = Object.assign({}, defaultInit, config);

        return new Promise((resolve, reject) => {
            fetch(url, init).then((response) => {
                then1 = response;
                if (response.headers.get('content-type') && response.headers.get('content-type').match(/application\/json/)) {
                    return response.json();
                }
                return response;
            }).then(res2 => {
                const then2 = {data: res2};
                const result = Object.assign({}, then2, then1, {config: init});
                if (then1.ok) {
                    resolve(result);
                } else {
                    reject(result);
                }

            }).catch(err => reject(err));
        });
    },
    delete: function (url, config) {
        let then1 = {};
        const defaultInit = {
            method: 'DELETE',
            timeout: timeout,
        };
        const init = Object.assign({}, defaultInit, config);

        return new Promise((resolve, reject) => {
            fetch(url, init).then((response) => {
                then1 = response;
                if (response.headers.get('content-type') && response.headers.get('content-type').match(/application\/json/)) {
                    return response.json();
                }
                return response;
            }).then(res2 => {
                const then2 = {data: res2};
                const result = Object.assign({}, then2, then1, {config: init});
                if (then1.ok) {
                    resolve(result);
                } else {
                    reject(result);
                }
            }).catch(err => reject(err));
        });
    },
    v2: function (url, data = {}, config = {}) {

        let body = (this.isObject(data) && config.files !== true) ? JSON.stringify(data) : data;

        const defaultInit = {
            method: 'GET',
            timeout: timeout,
            progress: null,
            headers: {},
        };
        const init = Object.assign({}, defaultInit, config);

        return new Promise((resolve, reject) => {
            const request = new XMLHttpRequest();
            request.open(init.method, url);
            request.upload.addEventListener('progress', function (e) {
                if (init.progress) {
                    return init.progress(e);
                }
            });
            request.onreadystatechange = (e) => {
                const responseHeaders = request.responseHeaders;
                if (request.readyState !== 4) {
                    return;
                }
                let result = request.response;
                if (responseHeaders && responseHeaders['Content-Type'] && responseHeaders['Content-Type'].match(/application\/json/)) {
                    result = JSON.parse(request.response);
                }
                if (request.status >= 200 && request.status < 300) {
                    resolve(result);
                } else {
                    reject(result);
                }
            };

            Object.keys(init.headers).forEach(function (item) {
                request.setRequestHeader(item, init.headers[item]);
            });

            request.send(body);
        });
    },
};

export default Connection;