Javascript join multiple arrays with & but I get duplicates-CodePudding

I have this project in which I create a link with multiple arrays that are joined with & signs. It works perfectly, but when I get more than 3 arrays, it doesn't. When I skip a couple of questions I get a & sign at the beginning of the string and when I only choose the first it adds one to the end which is bad. Also if I choose the first and the last array and skip the rest there a multiple & added between while I always just want 1.

I use this to join the arrays:

/**
         * Returns the parameters for the URL.
         *
         * @returns {string}
         */
        getLink() {
            this.tmp = [];
            for (let i = 0; i < this.url.length; i  ) {
                // Check if question is from the same quiz part and adds a , between chosen answers and add the right prefix at the beginning
                if (this.url[i].length > 0) {
                    this.tmp.push(""   Quiz[i].prefix   this.url[i].join(","))
                }
                // if the link is empty remove everything that was added (& an ,)
                if (this.url[i].length === 0) {
                    this.tmp.push("");
                }
            }
            /// If answers are from different quiz parts add a & between answers
            return ""   this.tmp.join("&");
        }

Quiz and this.url are the arrays and .prefix and stuff are keys of the arrays.

This is what I use to check the link string to remove the unwanted & signs:

        LinkChecker(link) {
            let cleanLink = link.split('&&').join('&');
            if (cleanLink[0] === '&') {
                cleanLink = cleanLink.slice(1);
            }
            if (cleanLink[cleanLink.length - 1] === '&') {
                cleanLink = cleanLink.slice(0, -1);
            }
            return cleanLink;
            console.log(cleanLink.length)
        }

And this is something I tried now:

            let i = 0;
            let LastLink = '';
            let FirstLink = LastLink;
            let link = this.LinkChecker(this.getLink());
            if (link[link.length -1] === '&'){
                LastLink = link.slice(0, -1);
            }
            while(i == '&'){
                if(LastLink[i] === '&'){
                    FirstLink = link.slice(-1, 0);
                }
                i  
            }
            console.log(FirstLink)

But it also doesn't really work.

Preview:

bd_shoe_size_ids=6621&&&

&&manufacturer_ids=5866

bd_shoe_size_ids=6598&&&manufacturer_ids=5866

It's supposed to look like:

bd_shoe_size_ids=6598&manufacturer_ids=5866

CodePudding user response：

It is better to avoid than to fix (the double &).

Remove the whole block that does push(""). This push is adding an entry to your array that you really don't want to have at all, so just don't push it.

CodePudding user response：

Your LinkChecker method only considers pairs of &s. You can handle any number of &s by splitting and filtering out any empty entries in the array:

      LinkChecker(link) {
            // split by & and then filter out the blank entries
            let cleanLink = link
                .split('&')
                .filter((section) => section !== '') // remove any empty strings
                .join('&');
            if (cleanLink[0] === '&') {
                cleanLink = cleanLink.slice(1);
            }
            if (cleanLink[cleanLink.length - 1] === '&') {
                cleanLink = cleanLink.slice(0, -1);
            }
            return cleanLink;
            console.log(cleanLink.length)
        }

As others have mentioned, there are ways to solve this in your array creation but since your LinkChecker seems to be where you are cleaning them specifically, I only changed that method for the sake of clarity.