如何将元素存储到数组中，并检查是否存在值？

Question

I am creating a form that allows you to sign up for alerts on our website, by allowing a user to input the keywords into a form.

I have setup the validation, although the jquery I have used seems somewhat convoluted even to me, it works!

I am now trying to setup the form so that when you input a keyword, it checks to see if you have already put in that keyword.

e.g. I've added "cloud" to my list, and I accidentally try to add it again, the form should alert me and not allow me to add it to my list.

I think the solution would be to store the keyword in a "KeywordList" array, then cycle through using a for each loop like in PHP:

foreach (KeywordList as KeywordListArrayElement){
         if(KwValue == KeywordListArrayElement){
           alert ("The keyword '+KwValue+' has already been added");
           return false;
         }
}

But I don't know how to store the Keyword in the array or fetch it from it

here is my html:

    <form action="" method="get" name="Test Form" target="_self" id="alerts_form" dir="ltr" lang="en">
        <fieldset id="alerts_options">
            <label for="email_address">Email: </label>
            <input type="text" id="email_address" name="email_address" tabindex="1" autofocus="autofocus" autocomplete="on" required="required" value="" /><div class="email-alert form_val" style="display: none;">Please enter a valid email address</div><br />
            <label for="keywords">Keyword(s): </label>
            <input type="text" id="keywords" name="keywords[]" tabindex="2" autocomplete="on" value="" />
            <button id="addKeyword" name="addKeyword" value="">+</button><br />
            <div id="KeywordList"></div>
            <div class="keyword-alert form_val" style="display: none;">Please input at least one keyword</div>
            <label for="frequency">Frequency: </label>
            <select tabindex="3" id="frequency" name="frequency"><br />
            <optgroup>
            <option selected="selected" value=""></option>
            <option value="1">Daily</option>
            <option value="7">Weekly</option>
            <option value="30">Monthly</option>
            </optgroup>
            </select><div class="frequency-alert form_val" style="display: none;">Please make a selection</div><br />
            <input type="hidden" id="Step" name="Step" value="2" />
            <div class="clear"></div>
            <button class="alert_button" type="submit" id="submit" name="UpdateAlertOption" value="Unconfirmed">Submit</button><br />
            <button class="alert_button" type="submit" name="UpdateAlertOption" value="Delete">Delete</button><br />
            <button class="alert_button" type="submit" name="UpdateAlertOption" value="Delete All">DeleteAll</button>
            <input type="hidden" value="" name="" class="KwdBox" />
        </fieldset>
    </form>

Here is my JQuery:

<script type='text/javascript'>
jQuery(document).ready(function($){

    $("#addKeyword").click(function(event) {
    event.preventDefault();
    var KwValue = $("#keywords").val();
    if($("#keywords").val()==""){
        alert('Please input a keyword');
        }

        else
        {
            var squareBrackets = "[]";

                $("#keywords").css('background-color', '#FFFFFF');
                $("#alerts_options .keyword-alert").hide();
            $('<input type="text" class="KwdBox" name="keywords'+squareBrackets+'" value="'+KwValue+'" tabindex="2" autocomplete="on" required="required"/>')
            .appendTo('#KeywordList');
            $("#keywords").val("");
            $(".KwdBox").click(function(event){
                event.preventDefault();
                $(this).remove();

            });
        }
    });

    $("#alerts_options .email-alert").hide();
    $("#alerts_options .keyword-alert").hide();
    $("#alerts_options .frequency-alert").hide();

    $("#submit").click(function(){


        var frequency = 1;
        if($("[name=frequency]").val()==""){
        frequency = 0;
        }else{
        frequency = 1;
        }
        var keyword = 1;
        if($("#keywords").val()=="") {
        keyword = 0;
        }
        if($(".KwdBox").val() >""){
        keyword = 1;
        }
        var email = 1;
        if(!checkEmail($("[name=email_address]").val())){
        email = 0;
        }else{
        email = 1;
        }
        //frequency empty, email empty, kw empty
        if(frequency == 0 && email == 0 && keyword == 0){
            $("#keywords").css('background-color', 'rgb(255, 232, 232)');
            $("[name=email_address]").css('background-color', 'rgb(255, 232, 232)');
            $("[name=frequency]").css('background-color', 'rgb(255, 232, 232)');        
            $("#alerts_options .form_val").show();
            return false;
        }
        else{
            $("#alerts_options .form_val").hide();
        } //frequency empty, email on, kw empty
        if(frequency == 0 && email > 0 && keyword == 0){
            $("#keywords").css('background-color', 'rgb(255, 232, 232)');
            $("[name=email_address]").css('background-color', '#FFFFFF');
            $("[name=frequency]").css('background-color', 'rgb(255, 232, 232)');    
            $("#alerts_options .email-alert").hide();
            $("#alerts_options .keyword-alert").show();
            $("#alerts_options .frequency-alert").show();
            return false;
        }//frequency empty, email on, kw on
        if(frequency == 0 && email > 0 && keyword > 0){
            $("#keywords").css('background-color', '#FFFFFF');
            $("[name=email_address]").css('background-color', '#FFFFFF');
            $("[name=frequency]").css('background-color', 'rgb(255, 232, 232)');
            $("#alerts_options .email-alert").hide();
            $("#alerts_options .keyword-alert").hide();
            $("#alerts_options .frequency-alert").show();
            return false;
        }//frequency on, email on, kw empty
        if(frequency > 0 && email > 0 && keyword == 0){
            $("#keywords").css('background-color', 'rgb(255, 232, 232)');
            $("[name=email_address]").css('background-color', '#FFFFFF');
            $("[name=frequency]").css('background-color', '#FFFFFF');
            $("#alerts_options .email-alert").hide();
            $("#alerts_options .keyword-alert").show();
            $("#alerts_options .frequency-alert").hide();
            return false;
        }
        if(frequency > 0 && email == 0 && keyword > 0){
            $("#keywords").css('background-color', '#FFFFFF');
            $("[name=email_address]").css('background-color', 'rgb(255, 232, 232)');
            $("[name=frequency]").css('background-color', '#FFFFFF');
            $("#alerts_options .email-alert").show();
            $("#alerts_options .keyword-alert").hide();
            $("#alerts_options .frequency-alert").hide();
            return false;
        }
        if(frequency == 0 && email == 0 && keyword > 0){
            $("#keywords").css('background-color', '#FFFFFF');
            $("[name=email_address]").css('background-color', 'rgb(255, 232, 232)');
            $("[name=frequency]").css('background-color', 'rgb(255, 232, 232)');
            $("#alerts_options .email-alert").show();
            $("#alerts_options .keyword-alert").hide();
            $("#alerts_options .frequency-alert").show();
            return false;
        }
            if(frequency > 0 && email == 0 && keyword == 0){
            $("#keywords").css('background-color', 'rgb(255, 232, 232)');
            $("[name=email_address]").css('background-color', 'rgb(255, 232, 232)');
            $("[name=frequency]").css('background-color', '#FFFFFF');
            $("#alerts_options .email-alert").show();
            $("#alerts_options .keyword-alert").show();
            $("#alerts_options .frequency-alert").hide();
            return false;
        }

    });
});
</script>

Answer 1

You don't have to use an array. Use a map/associative-array instead. You can do something like this:

var keywords = {};

Then if your keyword is in the variable keyword, you can do:

keywords[keyword] = true;

So if you had the keyword cloud, what you basically have is:

keywords['cloud'] = true;

To check for its existence, all you have to do is:

if(keywords[keyword]) {
  ...
}

Now to add your keywords to the list, you can do something like this:

var KwValue = $("#keywords").val();

var keywordArray = KwValue.split(/\s*,\s*/); //assuming that your keywords are separated by commas:

for(var i = 0; i < keywordArray.length; i++) {
    var keyword = keywordArray[i];

    if(!keywords[keyword]) {
       keywords[keyword] = true;
       ...
    }
}

This is O(n), but it is better than the O(n²) you would get with an array.