@writ/utils/jsonp.js

My tool kit

'use strict';


function destroy(sid, tid) {
    var script = document.getElementById(sid);
    if (script) {
        document.getElementsByTagName('head')[0].removeChild(script);
    }
    if (tid) {
        clearTimeout(sid);
    }
    try {
        delete window[sid];
    } catch (e) {
        window[sid] = undefined;
    }
}

function JsonpError(message) {
    this.message = message;
}
JsonpError.prototype = new Error;
JsonpError.prototype.constructor = JsonpError;
JsonpError.prototype.name = 'JsonpError';

/**
 * 
 * @param {string} url 请求的地址 
 * @param {object} option 请求的配置项
 * @param {number} option.timeout 请求的超时时间
 * @param {string} option.charset 请求使用的字符集
 * @param {string} option.callback 与被请求地址约定的callback名称  
 */
export default function jsonp(url, option) {
    if ('string' !== typeof url) {
        throw new Error('[Jsonp Error] `url` must be a string!');
    }

    option = 'object' === typeof option && option ? option : {};

    const callback = option.callback ? option.callback.toString() : 'callback';
    const timeout = !isNaN(option.timeout) && option.timeout > 0 ? option.timeout : 10000;
    const charset = option.charset ? option.charset : (document.characterSet || document.charset);
    const sid = Date.now() + '_' + Math.floor(Math.random() * 100000);
    let timer;

    return new Promise(function (resolve, reject) {
        const script = document.createElement('script');

        url += (url.indexOf('?') === -1) ? '?' : '&';
        script.src = url.concat(`${callback}=${sid}`);
        script.charset = charset;
        script.id = sid;

        window[sid] = function (res) {
            destroy(sid, timer);
            resolve(res);
        };
        timer = setTimeout(function () {
            destroy(sid, timer);
            reject(new JsonpError('Request timeout.'));
        }, timeout);

        script.onerror = function () {
            destroy(sid, timer);
            reject(new JsonpError('Request error.'));
        };

        document.getElementsByTagName('head')[0].appendChild(script);
    });
}