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Cant get indexOf statement to work

Ultimately I am prompting the user for a guess, which is then ultimately changed so regardless of what the user inputs it will always Capitalize the first letter and make the rest lowercase. (Im doing this so if the user types in a guess the string will either match or not match the values in an array.) I tried doing a for statement to use a loops counter (3 total guesses is what im looking for). But when I try to use a indexOf to check the array, I keep getting an "unexpected token" error on that line that contains the indexOf statement. So the question would be (1) what am i doing wrong in this line of code?
//declare variables
var sportsArray = new Array("Football", "Basketball", "Rollerblading", "Hiking", "Biking", "Swimming");
var name = prompt("Enter your name");
var loops = 0;
var score = 0;
var sGuess = prompt("enter your sport guess");
// uses substrings to ultimately capitalize the 1st letter, and make everything after it lowerCase.
var sFirstPart = sGuess.substr(0, 1);
var sFirstCap = sFirstPart.toUpperCase();
var sSecondPart = sGuess.substring(1, sGuess.length);
var sSecondLow = sSecondPart.toLowerCase();
var usableGuess = sFirstCap + sSecondLow;
while(loops < 4){
if(sportsArray.indexOf(usableGuess) = 0 {
document.write("nice guess");
loops++;
}else {
document.write("loser");
loops++;
}
}

This works for checking the whole array:
var sportsArray = new Array("Football", "Basketball", "Rollerblading", "Hiking", "Biking", "Swimming");
var name = prompt("Enter your name");
var loops = 0;
var score = 0;
var sGuess = prompt("enter your sport guess");
// uses substrings to ultimately capitalize the 1st letter, and make everything after it lowerCase.
var sFirstPart = sGuess.substr(0, 1);
var sFirstCap = sFirstPart.toUpperCase();
var sSecondPart = sGuess.substring(1, sGuess.length);
var sSecondLow = sSecondPart.toLowerCase();
var usableGuess = sFirstCap + sSecondLow;
while(loops < 4){
if(sportsArray.indexOf(usableGuess) > -1) {
document.write("nice guess");
loops++;
}else {
document.write("loser");
loops++;
}
}
You'd want to use indexOf(guess) > -1 to check if the guess is present at any index of the array. For checking just one index position it would be indexOf(guess) == 0.

sportsArray.indexOf(usableGuess) === 0) instead of sportsArray.indexOf(usableGuess) = 0
It's a good practice to check for equality with constant on the left side. It will throw an exception in most browsers:
var a = 3;
if (12 = a) { // throws ReferenceError: invalid assignment left-hand side in Firefox
//do something
}
Also: use tools that provide static code analysis. A jslint.com or jshint.com for js is a good choice. There are also IDE plugins explicitely for that (using either of those two and more), see Is there a working JSLint Eclipse plug-in?.

Javascript array length through user input

I have a problem in Javascript I want to make a form which have one input text field and one button when I click on the button window.prompt is called.
It will prompt depend upon my array length but I want array length get through input text field when I write 10 it will prompt 10 times when I write 2 it will prompt 2 times.
How can i write this type of query?
I tried this code but its not working.
words = new Array (4);
function a() {
for ( k = 0 ; k < words.length ; k = k + 1 ) {
words[ k ] = window.prompt( "Enter word # " + k, "" ) ;
}
}

Maybe you forgot to call your function a().
Some remarks about your code:
You don't have to specify an initial array size, e.g. words = [] or words = new Array() is enough.
Also k=k+1 is usually written as k++.
A remark about asking questions:
Use punctuation to make sentences! Your whole question is one sentence.

Hopefully it's just the snippet of code but I hope you are using var somewhere to declare all those variables.
Otherwise this should do the trick, however not sure what you are trying to achieve but this sounds like a bad user experience.
Here is the jsffidle http://jsfiddle.net/R2bCz/1/
function Handler(event) {
var count = event.target.value;
var i = 0;
var words = [];
var word;
for (; i < count; i++) {
word = window.prompt("Enter word # " + i, "");
words.push(word);
}
}
$("#multi").on("change", Handler);

Regex not matching properly

Ive been working on this regex for days now and I cant get it figured out. It either passes everything I put in there or it kicks everything out and I cannot seem to make it function. Admittedly I am new to doing this complex of stuff with Javascript so It may be that you realy cant do this.
I want to check onkeypress what was entered into the input and then validate it to x, y, or z. Then from there send it on about its way to do other neat stuff.
So the question is what the heck am I not understanding about RegExp?
Here is a FIDDLE for it.
function val() {
var gradeIn = document.querySelectorAll("#letGrade input[type=text]");
var checkGrade = new RegExp(/[xyz]/gi);
for (var i = 0; i < gradeIn.length; i++) {
if (!checkGrade.test(gradeIn.value)) {
alert ("This must be X, Y, or Z");
return false;
} else {
return true;
}
}
};
EDIT/UPDATE:
I was trying to do this on keypress and validate each text input individualy however this was realy kinda squishy in the grand scheme of things and not working out exactly correct. I decided to validate all text inputs onsubmit and have everything go all at once. Updated code is below.
function calcGPA() {
var grades = document.querySelectorAll("#letGrade input[type=text]");
var contacts = document.querySelectorAll("#conHours input[type=text]");
var gVals = [];
var cVals = [];
var failGrade = "The Letter Grade input may only be A, B, C, D or F";
var failHours = "The Contact Hours input may only be 1, 2, 3, 4 or 5";
var checkGrade = /^[ABCDF]/;
var checkhours = /^[12345]/;
for (var i = 0; i < grades.length; i++) {
if (!checkGrade.test(grades[i].value)) {
alert(failGrade);
return false;
}
if (!checkhours.test(contacts[i].value)) {
alert(failHours);
return false;
}
gVals.push(grades[i].value);
cVals.push(contacts[i].value);
}
//Other cool stuff happens here
};
Now to just finish the conversion piece for the letters to numbers and the math piece. Thank you for your help on this!

The problem's not only with your regular expression.
if (!checkGrade.test(gradeIn[i].value)) {
You weren't checking each grade. Now if you want it to only be those characters, you have to extend the regular expression a bit. Also, there's no point calling new RegExp if you're using native syntax.
var checkGrade = /^[xyz]+$/;
That means that you're OK with the fields being like "xxyyz" or "zzy". If it should just be one character, that'd be
var checkGrade = /^[xyz]$/;

Searching for most performant way for string replacing with javascript

I'm programming my own autocomplete textbox control using C# and javascript on clientside. On client side i want to replace the characters in string which matching the characters the user was searching for to highlight it. For example if the user was searching for the characters 'bue' i want to replace this letters in the word 'marbuel' like so:
mar<span style="color:#81BEF7;font-weight:bold">bue</span>l
in order to give the matching part another color. This works pretty fine if i have 100-200 items in my autocomplete, but when it comes to 500 or more, it takes too mutch time.
The following code shows my method which does the logic for this:
HighlightTextPart: function (text, part) {
var currentPartIndex = 0;
var partLength = part.length;
var finalString = '';
var highlightPart = '';
var bFoundPart = false;
var bFoundPartHandled = false;
var charToAdd;
for (var i = 0; i < text.length; i++) {
var myChar = text[i];
charToAdd = null;
if (!bFoundPart) {
var myCharLower = myChar.toLowerCase();
var charToCompare = part[currentPartIndex].toLowerCase();
if (charToCompare == myCharLower) {
highlightPart += myChar;
if (currentPartIndex == partLength - 1)
bFoundPart = true;
currentPartIndex++;
}
else {
currentPartIndex = 0;
highlightPart = '';
charToAdd = myChar;
}
}
else
charToAdd = myChar;
if (bFoundPart && !bFoundPartHandled) {
finalString += '<span style="color:#81BEF7;font-weight:bold">' + highlightPart + '</span>';
bFoundPartHandled = true;
}
if (charToAdd != null)
finalString += charToAdd;
}
return finalString;
},
This method only highlight the first occurence of the matching part.
I use it as follows. Once the request is coming back from server i build an html UL list with the matching items by looping over each item and in each loop i call this method in order to highlight the matching part.
As i told for up to 100 items it woks pretty nice but it is too mutch for 500 or more.
Is there any way to make it faster? Maybe by using regex or some other technique?
I also thought about using "setTimeOut" to do it in a extra function or maybe do it only for the items, which currently are visible, because only a couple of items are visible while for the others you have to scroll.

Try limiting visible list size, so you are only showing 100 items at maximum for example. From a usability standpoint, perhaps even go down to only 20 items, so it would be even faster than that. Also consider using classes - see if it improves performance. So instead of
mar<span style="color:#81BEF7;font-weight:bold">bue</span>l
You will have this:
mar<span class="highlight">bue</span>l

String replacement in JavaScript is pretty easy with String.replace():
function linkify(s, part)
{
return s.replace(part, function(m) {
return '<span style="color:#81BEF7;font-weight:bold">' + htmlspecialchars(m) + '</span>';
});
}
function htmlspecialchars(txt)
{
return txt.replace('<', '<')
.replace('>', '>')
.replace('"', '"')
.replace('&', '&');
}
console.log(linkify('marbuel', 'bue'));

I fixed this problem by using regex instead of my method posted previous. I replace the string now with the following code:
return text.replace(new RegExp('(' + part + ')', 'gi'), "<span>$1</span>");
This is pretty fast. Much faster as the code above. 500 items in the autocomplete seems to be no problem. But can anybody explain, why this is so mutch faster as my method or doing it with string.replace without regex? I have no idea.
Thx!

Fastest way to search string in javascript

I have a hidden field on my page that stores space separated list of emails.
I can have maximum 500 emails in that field.
What will be the fastest way to search if a given email already exists in that list?
I need to search multiple emails in a loop
use RegEx to find a match
use indexOf()
convert the list to a
javascript dictionary and then
search
If this is an exact duplicate, please let me know the other question.
Thanks
EDIT:
Thanks everyone for your valuable comments and answers.
Basically my user has a list of emails(0-500) in db.
User is presented with his own contact list.
User can then choose one\more emails from his contact list to add to the list.
I want to ensure at client side that he is not adding duplicate emails.
Whole operation is driven by ajax, so jsvascript is required.

The answer is: It depends.
It depends on what you actually want to measure.
It depends on the relationship between how many you're searching for vs. how many you're searching.
It depends on the JavaScript implementation. Different implementations usually have radically different performance characteristics. This is one of the many reasons why the rule "Don't optimize prematurely" applies especially to cross-implementation JavaScript.
...but provided you're looking for a lot fewer than you have in total, it's probably String#indexOf unless you can create the dictionary once and reuse it (not just this one loop of looking for X entries, but every loop looking for X entries, which I tend to doubt is your use-case), in which case that's hands-down faster to build the 500-key dictionary and use that.
I put together a test case on jsperf comparing the results of looking for five strings buried in a string containing 500 space-delimited, unique entries. Note that that jsperf page compares some apples and oranges (cases where we can ignore setup and what kind of setup we're ignoring), but jsperf was being a pain about splitting it and I decided to leave that as an exercise for the reader.
In my tests of what I actually think you're doing, Chrome, Firefox, IE6, IE7 and IE9 did String#indexOf fastest. Opera did RegExp alternation fastest. (Note that IE6 and IE7 don't have Array#indexOf; the others do.) If you can ignore dictionary setup time, then using a dictionary is the hands-down winner.
Here's the prep code:
// ==== Main Setup
var toFind = ["aaaaa100#zzzzz", "aaaaa200#zzzzz", "aaaaa300#zzzzz", "aaaaa400#zzzzz", "aaaaa500#zzzzz"];
var theString = (function() {
var m, n;
m = [];
for (n = 1; n <= 500; ++n) {
m.push("aaaaa" + n + "#zzzzz");
}
return m.join(" ");
})();
// ==== String#indexOf (and RegExp) setup for when we can ignore setup
var preppedString = " " + theString + " ";
// ==== RegExp setup for test case ignoring RegExp setup time
var theRegExp = new RegExp(" (?:" + toFind.join("|") + ") ", "g");
// ==== Dictionary setup for test case ignoring Dictionary setup time
var theDictionary = (function() {
var dict = {};
var index;
var values = theString.split(" ");
for (index = 0; index < values.length; ++index) {
dict[values[index]] = true;
}
return dict;
})();
// ==== Array setup time for test cases where we ignore array setup time
var theArray = theString.split(" ");
The String#indexOf test:
var index;
for (index = 0; index < toFind.length; ++index) {
if (theString.indexOf(toFind[index]) < 0) {
throw "Error";
}
}
The String#indexOf (ignore setup) test, in which we ignore the (small) overhead of putting spaces at either end of the big string:
var index;
for (index = 0; index < toFind.length; ++index) {
if (preppedString.indexOf(toFind[index]) < 0) {
throw "Error";
}
}
The RegExp alternation test:
// Note: In real life, you'd have to escape the values from toFind
// to make sure they didn't have special regexp chars in them
var regexp = new RegExp(" (?:" + toFind.join("|") + ") ", "g");
var match, counter = 0;
var str = " " + theString + " ";
for (match = regexp.exec(str); match; match = regexp.exec(str)) {
++counter;
}
if (counter != 5) {
throw "Error";
}
The RegExp alternation (ignore setup) test, where we ignore the time it takes to set up the RegExp object and putting spaces at either end of the big string (I don't think this applies to your situation, the addresses you're looking for would be static):
var match, counter = 0;
for (match = theRegExp.exec(preppedString); match; match = theRegExp.exec(preppedString)) {
++counter;
}
if (counter != 5) {
throw "Error";
}
The Dictionary test:
var dict = {};
var index;
var values = theString.split(" ");
for (index = 0; index < values.length; ++index) {
dict[values[index]] = true;
}
for (index = 0; index < toFind.length; ++index) {
if (!(toFind[index] in dict)) {
throw "Error";
}
}
The Dictionary (ignore setup) test, where we don't worry about the setup time for the dictionary; note that this is different than the RegExp alternation (ignore setup) test because it assumes the overall list is invariant:
var index;
for (index = 0; index < toFind.length; ++index) {
if (!(toFind[index] in theDictionary)) {
throw "Error";
}
}
The Array#indexOf test (note that some very old implementations of JavaScript may not have Array#indexOf):
var values = theString.split(" ");
var index;
for (index = 0; index < toFind.length; ++index) {
if (values.indexOf(toFind[index]) < 0) {
throw "Error";
}
}
The Array#indexOf (ignore setup) test, which like Dictionary (ignore setup) assumes the overall list is invariant:
var index;
for (index = 0; index < toFind.length; ++index) {
if (theArray.indexOf(toFind[index]) < 0) {
throw "Error";
}
}

Instead of looking for the fastest solution, you first need to make sure that you’re actually having a correct solution. Because there are four cases an e-mail address can appear and a naive search can fail:
Alone: user#example.com
At the begin: user#example.com ...
At the end: ... user#example.com
In between: ... user#example.com ...
Now let’s analyze each variant:
To allow arbitrary input, you will need to escape the input properly. You can use the following method to do so:
RegExp.quote = function(str) {
return str.toString().replace(/(?=[.?*+^$[\]\\(){}-])/g, "\\");
};
To match all four cases, you can use the following pattern:
/(?:^|\ )user#example\.com(?![^\ ])/
Thus:
var inList = new RegExp("(?:^| )" + RegExp.quote(needle) + "(?![^ ])").test(haystack);
Using indexOf is a little more complex as you need to check the boundaries manually:
var pos = haystack.indexOf(needle);
if (pos != -1 && (pos != 0 && haystack.charAt(pos-1) !== " " || haystack.length < (pos+needle.length) && haystack.charAt(pos+needle.length) !== " ")) {
pos = -1;
}
var inList = pos != -1;
This one is rather quite simple:
var dict = {};
haystack.match(/[^\ ]+/g).map(function(match) { dict[match] = true; });
var inList = dict.hasOwnProperty(haystack);
Now to test what variant is the fastest, you can do that at jsPerf.

indexOf() is most probably the fastest just keep in mind you need to search for two possible cases:
var existingEmails = "email1, email2, ...";
var newEmail = "somethingHere#email.com";
var exists = (existingEmails.indexOf(newEmail + " ") >= 0) || (existingEmails.indexOf(" " + newEmail ) > 0);

You're asking a question with too many unstated variables for us to answer. For example, how many times do you expect to perform this search? only once? A hundred times? Is this a fixed list of emails, or does it change every time? Are you loading the emails with the page, or by AJAX?
IF you are performing more than one search, or the emails are loaded with the page, then you are probably best off creating a dictionary of the names, and using the Javascript in operator.
If you get the string from some off-page source, and you only search it once, then indexOf may well be better.
In all cases, if you really care about the speed, you're best off making a test.
But then I'd ask "Why do you care about the speed?" This is a web page, where loading the page happens at network speeds; the search happens at more or less local-processor speed. It's very unlikely that this one search will make a perceptible difference in the behavior of the page.

Here is a little explanation:
Performing a dictionary lookup is relatively complicated - very fast compared with (say) a linear lookup by key when there are lots of keys, but much more complicated than a straight array lookup. It has to calculate the hash of the key, then work out which bucket that should be in, possibly deal with duplicate hashes (or duplicate buckets) and then check for equality.
As always, choose the right data structure for the job - and if you really can get away with just indexing into an array (or List) then yes, that will be blindingly fast.
The above has been taken from one of the blog posts of #Jon Skeet.

I know this is an old question, but here goes an answer for those who might need in the future.
I made some tests and the indexOf() method is impossibly fast!
Tested the case on Opera 12.16 and it took 216µs to search and possibly find something.
Here is the code used:
console.time('a');
var a=((Math.random()*1e8)>>0).toString(16);
for(var i=0;i<1000;++i)a=a+' '+((Math.random()*1e8)>>0).toString(16)+((Math.random()*1e8)>>0).toString(16)+((Math.random()*1e8)>>0).toString(16)+((Math.random()*1e8)>>0).toString(16);
console.timeEnd('a');
console.time('b');
var b=(' '+a).indexOf(((Math.random()*1e8)>>0).toString(16));
console.timeEnd('b');
console.log([a,b]);
In the console you will see a huge output.
The timer 'a' counts the time taken to make the "garbage", and the timer 'b' is the time to search for the string.
Just adding 2 spaces, one before and one after, on the email list and adding 1 space before and after the email, you are set to go.
I use it to search for a class in an element without jQuery and it works pretty fast and fine.