解析url地址栏中的字段

 如果要解析以下地址中的channel_tag字段 http://saas.ceshi.test.maiyiru.com/invoice/?channel_tag=meituan&keyword=222http://saas.wulongmei.test.maiyatian.com/invoice/?channel_tag=meituan&keyword=222

var href = window.location.href || '你的url地址'
var query = getQueryVariable( href, '你要查询的字段' ) || ''

var getQueryVariable = function (url, key) {
    if (!url || !key) return ''
    let ret = getQueryVariables(url, key);
    return ret[key] || ''
}

var getQueryVariables = function (url) {
    if (!url) return ''
    let ret                 = {},
        seg                 = url.substr(url.indexOf('?') + 1, url.length).split('&'),
        len = seg.length, i = 0, s
    for (; i < len; i++) {
        if (!seg[i]) {
            continue
        }
        s         = seg[i].split('=')
        ret[s[0]] = s[1]
    }

    return ret
}

console.log(query)