【正则】根据自定的匹配规则生成url

题目

    const source_path = "demo/xixi/haha/abc12323.html"            // 原始请求url
    const math_rule = "/xixi/${_id}/abc${cid}.html$"              // 匹配规则
    const target_path = "http://127.0.0.1:8001/gg/${cid}/${_id}"; // 目标url

说明：如果匹配的规则命中原始url则将目标url替换成匹配命中的路径,若未命中返回null；上述例子应返回：

http://127.0.0.1:8001/gg/12323/haha

解答

    function changeTargetUrl(source_path,math_rule,target_path) {
        // 将math_rule中变量进行正则替换  /\/xixi\/(.+)\/abc(.+).html$/
        const reg = math_rule.replace('/','\/').replace(/\$\{(.+?)\}/g, '(.+)')
        // 从source_path中将变量的值取出
        // ["/xixi/haha/abc12323.html", "haha", "12323", index: 4, input: "demo/xixi/haha/abc12323.html", groups: undefined]
        const afterPickParams = source_path.match(reg)
        if (!afterPickParams) {
            return null
        }
        // 将math_rule中变量提取出来 ["${_id}", "${cid}"]
        const pickParams = math_rule.match(/\$\{(.+?)\}/g);
        // pickParams循环需要替换的变量，在afterPickParams中找出并替换
        for(let key in pickParams){
            const targetKey = pickParams[key]
            const pickObjIdx = Number(key)+1
            target_path=target_path.replace(targetKey, afterPickParams[pickObjIdx])
        }
        console.log(target_path)
        return target_path
    }