fetch封装

　　对fetch方法做简单的封装，完成需要统一处理的功能：antd - Table参数映射；取消短时间内的重复请求；options.params参数拼接到url；options.body转换json；headers.Authorization请求头认证赋值；请求异常统一处理；增删改成功提示

import {message} from 'antd';
import _ from '_';
import {cookieUtil} from './util';

const REQUEST_RECORD = {},
    DEFAULT_REQUEST_INTERVAL = 1000,
    DEFAULT_FETCH_OPTIONS = {
        method: 'GET',
        mode: 'cors',
        headers: {},
    },
    SHOW_MSG_METHOD = {
        POST: true,
        PUT: true,
        DELETE: true,
    };

/**
 * Requests a URL, returning a promise.
 *
 * @param  {string} url       The URL we want to request
 * @param  {object} [options] The options we want to pass to "fetch"
 * @return {object}           An object containing either "data" or "err"
 */
export default function request(url, options = {}) {
    options = handleTableParams(options);
    if (!isRepeatedRequest(url, options)) return null;
    const fetchUrl = generateUrl(url, options);
    const fetchOptions = generateOptions(options);
    return fetch(fetchUrl, fetchOptions)
        .then(checkStatus)
        .then(parseJSON)
        .then(data => {
            if (options['showMsg'] !== false && SHOW_MSG_METHOD[options.method]) {
                message.success(getMessage(options.method), 2);
            }
            return data;
        })
        .catch(() => {
            return null;
        });
}

function handleTableParams(options) {
    const params = (options.params = options.params || {});
    if (params.pagination) {
        params.current = options.pagination.current;
        params.pageSize = options.pagination.pageSize;
        delete params.pagination;
    }
    const filters = params.filters;
    if (filters) {
        Object.assign(params, filters);
        delete params.filters;
    }
    if (params.sorter) {
        const field = params.sorter.field,
            order = params.sorter.order;
        if (field && order) params[order] = field;
        delete params.sorter;
    }
    return options;
}

function isRepeatedRequest(url, options) {
    let record = REQUEST_RECORD[url],
        now = new Date().getTime();

    if (record && _.isEqual(record.options, options) && now - record.lastTime < DEFAULT_REQUEST_INTERVAL) return false;
    REQUEST_RECORD[url] = {
        options: _.assign({}, options),
        lastTime: now,
    };
    return true;
}

function generateUrl(url, options) {
    const params = options.params;
    if (typeof params === 'object') {
        let paramArray = [];
        Object.keys(params).forEach(key => {
            if (paramArray.length === 0) {
                paramArray.push('?');
            } else {
                paramArray.push('&');
            }
            paramArray.push(key);
            paramArray.push('=');
            paramArray.push(params[key]);
        });
        if (paramArray.length !== 0) {
            return url + paramArray.join('');
        }
    }
    return url;
}

function generateOptions(options) {
    const fetchOptions = _.assign({}, DEFAULT_FETCH_OPTIONS),
        method = options.method,
        data = options.body;
    options.method = options.method ? options.method.toUpperCase() : 'GET';
    if (method) fetchOptions.method = method;
    if (data && Object.prototype.toString.call(data) === '[object Object]') {
        fetchOptions.body = JSON.stringify(data);
        fetchOptions.headers['Content-Type'] = 'application/json';
    }
    const token = cookieUtil.getCookie('token');
    if (token) fetchOptions.headers.Authorization = token;
    return fetchOptions;
}

function checkStatus(response) {
    if (response.status >= 200 && response.status < 300) {
        return response;
    } else {
        var error = new Error(response.statusText);
        response.json().then(data => {
            message.error(data.message || data, 2);
            console.error(data);
        });
        throw error;
    }
}

function parseJSON(response) {
    return response.json();
}

function getMessage(method) {
    let sub = '';
    switch (method) {
        case 'POST':
            sub = '新增成功';
            break;
        case 'PUT':
            sub = '修改成功';
            break;
        case 'DELETE':
            sub = '删除成功';
            break;
        default:
            break;
    }
    return sub;
}