CODEWITHSUNDEEP
javascriptarraysfor-loopiteration
gibbypoo
gibbypoo

Reputation: 55

Appending text through loop iteration

Not sure why I'm having a hard time with this. I think it's getting late in the day probably but --

I'm pulling database values into an array. The current array is: [1,3]. I'm then stepping through the array and appending a prefix to the values (in this case: "&Plantkey=") in order for the final string to have the format of:

&Plantkey=1&Plantkey=3

Here's my code so far:

if (array[a].ParameterName == "Plantkey") {
        var plantKey = array[a].ParameterValue;
        var plantTemp = [];
        plantTemp = plantKey.split(",");


        for (var p = 0; p < plantTemp.length; p++) {
            var plantKeyString = ("&Plantkey=" + plantTemp[p]);


        }

    }

I'm only getting the last array value (&Plantkey=3). With javascript, it doesn't like me instantiating the "var plantKeyString" and adding the "+=" operator. If I instantiate the array above the for loop, like so:

    var plantKeyString;
    for (var p = 0; p < plantTemp.length; p++) {
        plantKeyString += ("&Plantkey=" + plantTemp[p]);


    }

Then I end up with a longer string, including the array values I want but it also pulls in the "undefined" value that it finds at the beginning so it looks like this:

undefined&Plantkey=1&Plantkey=3

I could easily look for the "undefined" and remove it but I'm sure the problem is with the loop iteration, not the data, obviously.

Any help would be greatly appreciated! Thanks!

Upvotes: 0

Views: 60

Answers (2)

owaism
owaism

Reputation: 1188

The reason you are getting only the last value in the first case is because you are redeclaring a new plantKeyString for each loop hence only the last declaration stays.

with the second solution just do the following and it should work:

    var plantKeyString="";
    for (var p = 0; p < plantTemp.length; p++) {
        plantKeyString += ("&Plantkey=" + plantTemp[p]);


    }

The reason you were getting the undefined at the beginning of your final result was because 'plantKeyString' is 'undefined' as you have not given it a value. In javascript all variables are undefined till you give them a value. So in the solution that I have provided you are just instantiating it with an empty string.

Upvotes: 3

albciff
albciff

Reputation: 18507

You can do it in a succinctly way simply using array join() method and add &Plantkey= at first as follows:

var plantKeyString = '&Plantkey=' + array.join('&Plantkey=');

For an [1,3] array this code produces what you expect: &Plantkey=1&Plantkey=3, try with this code sample:

var array = [1,3];
var plantKeyString = '&PlantKey=' + array.join('&PlantKey=');
alert(plantKeyString);

See join() description here

Upvotes: 2

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