how to check if the url contains multiple strings.

问题:

In the question how to check if the url contains a given string. Javascript/jquery the answer checks if the url contains a given string. I want to extend this to check if it contains two things name=franky && gender=male. I tried

if(window.location.href.indexOf("name=franky" && "gender=male") > -1)

which appeared to work initially, but with further testing I have found it seems to work if only one of name or gender is present. Where am I going wrong here?

回答1:

You could break it into two parts and call indexOf twice instead of trying to check for both strings in the same call. Something like this:

if(window.location.href.indexOf("name=franky") > -1 && 
    window.location.href.indexOf("gender=male") > -1)

回答2:

The .indexOf() function only looks for a single string. To test for two strings you need two calls to .indexOf() as per Christofer's answer:

if(window.location.href.indexOf("name=franky") > -1 && 
   window.location.href.indexOf("gender=male") > -1)

The reason I'm posting an answer too is to briefly explain how the && operator works: given expr1 && expr2, the && operator "Returns expr1 if it can be converted to false; otherwise, returns expr2."

What does "converted to false" mean? Basically null, undefined, 0, NaN and "" (empty string) are "falsy" and will be "converted to false". non-zero numbers, non-empty strings and any object are "truthy" and will be converted to true.

That means when you said "name=franky" && "gender=male" the && operator tests the first operand, finds that (in this case) it can't be converted to false, so it returns "gender=male". So the reason your code seemed to work some of the time is that in effect it was doing this:

if(window.location.href.indexOf("gender=male") > -1)

回答3:

Another generic approach

function CheckIfAllQueryStringsExist(url, qsCollection) {
    for (var i = 0; i < qsCollection.length; i++) {
        if (url.indexOf(qsCollection[i]) == -1) {
            return false;
        }
    }
    return true;
}

Call it like this.

var myUrl = window.location.href;
var queryStrings = ["name=franky", "gender=male"];
var allPresent = CheckIfAllQueryStringsExist(myUrl, queryStrings);