A nice wrapper around the browser's kind of broken fetch API

better-fetch.js

const handleFetchResponse = (resp) => {
    return resp.text().then((text) => {
        let data = text;

        const contentType = resp.headers.get("content-type");
        const isJSON = contentType && contentType.indexOf("application/json") >= 0;
        if (isJSON)
        {
            try {
              data = JSON.parse(text);
            } catch (err) {
                console.error('Failed to parse JSON!', err);
            }
        }

        if (!resp.ok)
        {
            const error = (data && data.message) || resp.statusText;
            return Promise.reject(error);
        }

        return data;
    });
};

const fetch = {
    fetch: window.fetch,
    
    get: (url, config = null) => {
        const options = {
            ...config,
            method: 'GET',
        };
        return window.fetch(url, options).then(handleFetchResponse);
    },
    post: (url, body, config = null) => {
        const options = {
            ...config,
            method: 'POST',
            headers: { 'Content-Type': 'application/json', ...config?.headers },
            body: JSON.stringify(body),
        };
        return window.fetch(url, options).then(handleFetchResponse);
    },
    put: (url, body, config = null) => {
        const options = {
            ...config,
            method: 'PUT',
            headers: { 'Content-Type': 'application/json', ...config?.headers },
            body: JSON.stringify(body),
        };
        return window.fetch(url, options).then(handleFetchResponse);
    },
    delete: (url, config = null) => {
        const options = {
            ...config,
            method: 'DELETE',
        };
        return window.fetch(url, options).then(handleFetchResponse);
    },
};