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I am trying to get 3 conditions in one if . But it's not working

I need to match three conditions so that the page can show the appropriate result for that filters. I tried adding the && between three of the conditions but it doesn't work.
I am not revealing the real code here, but I've shown it without the original var names.
if(localStorage.getItem("eg1") == 30000 && eg2 == 1 && eg3 == use){};
eg2 and eg3 are just variables, they are not localstorage.

It should be:
if((localStorage.getItem("eg1") == 30000) && (eg2 == 1) &&
(eg3== use)){};

Here is a bit cleaner way to do it:
const a = ["eg1", "eg2", "eg3"].map(e => localStorage.getItem(e));
if (a[0] == 30000 && a[1] == 1 && a[2] == use) {
//
}
And a less dynamic but shorter way to do it:
if ([30000, 1, use].map((e, i) => e == localStorage.getItem("eg" + i++)).includes(false)) {
}

Try to decompose the problem in order to analyze it better:
var e1 = localStorage.getItem("eg1") === 30000;
var e2 = eg2 === 1;
var e3 = eg3 === use;
I've used triple equal since i suppose you don't want type coercion.
Since you can't show the original code, if you don't put some log of your results it's quite difficult to imagine what variables can contain with appropriate level of certainty.
Sure is that looking to your conditions independently should help you to identify where your guesses fall to fix what appears as a simple branch condition.

localStorage.getItem returns the value as string.
Try using if(localStorage.getItem("eg1") == "30000" && eg2 == 1 && eg3 == use){};

Is there any way of determining which or statement is true in javascript?

So say I have an if statement:
if(a=='' || b==''){
//which is true?
}
Is it possible to determine which statement satisfied the if statement without doing a switch statement or another if statement to check?

You can define a token to store what condition was true:
var token = null;
if ((a == '' && (token = 'a')) || (b == '' && (token = 'b'))) {
// Here token has an 'a' or a 'b'. You can use numbers instead of letters
}
I think it's the simplest way to do what you want.

As others have said, you have to test the conditions separately, but you can kind of mix worlds.
var test1 = 1 == 1; // true
var test2 = 2 == 1; // false
if (test1 || test2) {
// If either conditions is true, we end up here.
// Do the common stuff
if (test1) {
// Handle test1 true
}
if (test2) {
// Handle test2 true
}
}

No, you have asked explicitly if one or both are true. There's no way to work out which of those sub-expressions is true without another conditional of some sort.
If you're interested in different behaviour based on which is true, you should probably separate them with a possibly-common bit, something like
either = false;
if (a == ' ') {
doActionsForA();
either = true;
}
if (b == ' ') {
doActionsForB();
either = true;
}
if (either) {
doActionsForAorB();
}

If you care about which of the two conditions is true the only way to find out is to test them separately, e.g.
if(a==''){
// ...
}
else if(b=='') {
// ...
}
Sometimes, especially in more complicated conditionals, it helps if you store the result of each condition and reuse it later on:
var isFoo = a == '';
var isBar = b == '';
// You can now use isFoo and isBar whenever it's convenient

the simple solution:
if ((ia=(a=='')) || (b=='')) {
// ia indicate whether the boolean expression a have been true.
// ia -> a has been true, b may have, !ia -> b has been true, a has not
}
there is no ib in the simple solution as it won't be always be set due to shortcut evaluation.
to cater for shortcut evaluation try:
if (((ia=(a=='') || (ib=(b=='')) && ((ib=(b=='')) || (ia=(a==''))) {
// ia, ib indicate whether the corresponding boolean expressions have been true
}

if(a=='' || b==''){
var x= a || b;
//if a is ''(falsy) x will be b, else a
}
var phone="";
var email="something";
if(phone=='' || email==''){
var x= (phone) ? 'phone':'email';
console.log(x); //email
}

jquery check variable values

In jQuery I have the following 4 variables.
var add
var city
var state
var zip
I need to check to see that any one of the above have a value.
If none have a value that is OK. If all of them have a value that is OK.
Just need to check that at least one of them do not have a value.
Not sure what is the most efficient way of doing this.

var check = [ add, city, state, zip ].every( function ( v ) { return !!v } )
Just for the sake of showing off.
Explaination: the every method loops through all the array and returns false if one of the conditions returns false and stops immediately the loop. If all the loops return true, true is returned.
PS: v is for "variable".

var check = (function(a, b, c, d) {
return !!a && !!b && !!c && !!d;
}(add, city, state, zip));
console.log(check);
another method... lets learn some new techniques today!
this will actually check to see if the value is not false. anything else is ok (strings, numerics, TRUE).

Simply
if (yourVar)
{
// if yourVar has value then true other wise false.
}
Hope thats what you required..

to check i a variable has a value assign it to it you can do:
var myVar
....
if (typeof myVar === 'undefined'){
// here goes your code if the variable doesn't have a value
}

if(!add || !city || !state || !zip) {
console.log('exists var with no value');
}

if( add.length == 0 || zip.length == 0 || city.length == 0 || state.length == 0) {
alert("at least one of the variables has no value");
}; else if (add.length == 0 & zip.length == 0 & city.length == 0 & state.length == 0) {
alert("all of the variables are empty");
}; else { alert("okay"); }

javascript not removing undefined objects from array

I've got an in page text search using JS, which is here:
$.fn.eoTextSearch = function(pat) {
var out = []
var textNodes = function(n) {
if (!window['Node']) {
window.Node = new Object();
Node.ELEMENT_NODE = 1;
Node.ATTRIBUTE_NODE = 2;
Node.TEXT_NODE = 3;
Node.CDATA_SECTION_NODE = 4;
Node.ENTITY_REFERENCE_NODE = 5;
Node.ENTITY_NODE = 6;
Node.PROCESSING_INSTRUCTION_NODE = 7;
Node.COMMENT_NODE = 8;
Node.DOCUMENT_NODE = 9;
Node.DOCUMENT_TYPE_NODE = 10;
Node.DOCUMENT_FRAGMENT_NODE = 11;
Node.NOTATION_NODE = 12;
}
if (n.nodeType == Node.TEXT_NODE) {
var t = typeof pat == 'string' ?
n.nodeValue.indexOf(pat) != -1 :
pat.test(n.nodeValue);
if (t) {
out.push(n.parentNode)
}
}
else {
$.each(n.childNodes, function(a, b) {
textNodes(b)
})
}
}
this.each(function() {
textNodes(this)
})
return out
};
And I've got the ability to hide columns and rows in a table. When I submit a search and get the highlighted results, there would be in this case, the array length of the text nodes found would be 6, but there would only be 3 highlighted on the page. When you output the array to the console you get this:
So you get the 3 tags which I was expecting, but you see that the array is actually consisting of a [span,undefined,span,undefined,undefined,span]. Thus giving me the length of 6.
<span>
<span>
<span>
[span, undefined, span, undefined, undefined, span]
I don't know why it's not stripping out all of the undefined text nodes when I do the check for them. Here's what I've got for the function.
performTextSearch = function(currentObj){
if($.trim(currentObj.val()).length > 0){
var n = $("body").eoTextSearch($.trim(currentObj.val())),
recordTitle = "matches",
arrayRecheck = new Array(),
genericElemArray = new Array()
if(n.length == 1){
recordTitle = "match"
}
//check to see if we need to do a recount on the array length.
//if it's more than 0, then they're doing a compare and we need to strip out all of the text nodes that don't have a visible parent.
if($(".rows:checked").length > 0){
$.each(n,function(i,currElem){
if($(currElem).length != 0 && typeof currElem != 'undefined'){
if($(currElem).closest("tr").is(":visible") || $(currElem).is(":visible")){
//remove the element from the array
console.log(currElem)
arrayRecheck[i] = currElem
}
}
})
}
if(arrayRecheck.length > 0){
genericElemArray.push(arrayRecheck)
console.log(arrayRecheck)
}
else{
genericElemArray.push(n)
}
genericElemArray = genericElemArray[0]
$("#recordCount").text(genericElemArray.length + " " +recordTitle)
$(".searchResults").show()
for(var i = 0; i < genericElemArray.length; ++i){
void($(genericElemArray[i]).addClass("yellowBkgd").addClass("highLighted"))
}
}
else{
$(".highLighted").css("background","none")
}
}
If you look at the code below "//check to see if we need to do a recount on the array length. ", you'll see where I'm stripping out the text nodes based off of the display and whether or not the object is defined. I'm checking the length instead of undefined because the typeof == undefined wasn't working at all for some reason. Apparently, things are still slipping by though.
Any idea why I'm still getting undefined objects in the array?
My apologies for such a big post!
Thanks in advance

I've modified your eoTextSearch() function to remove dependencies on global variables in exchange for closures:
$.fn.extend({
// helper function
// recurses into a DOM object and calls a custom function for every descendant
eachDescendant: function (callback) {
for (var i=0, j=this.length; i<j; i++) {
callback.call(this[i]);
$.fn.eachDescendant.call(this[i].childNodes, callback);
}
return this;
},
// your text search function, revised
eoTextSearch: function () {
var text = document.createTextNode("test").textContent
? "textContent" : "innerText";
// the "matches" function uses an out param instead of a return value
var matches = function (pat, outArray) {
var isRe = typeof pat.test == "function";
return function() {
if (this.nodeType != 3) return; // ...text nodes only
if (isRe && pat.test(this[text]) || this[text].indexOf(pat) > -1) {
outArray.push(this.parentNode);
}
}
};
// this is the function that will *actually* become eoTextSearch()
return function (stringOrPattern) {
var result = $(); // start with an empty jQuery object
this.eachDescendant( matches(stringOrPattern, result) );
return result;
}
}() // <- instant calling is important here
});
And then you can do something like this:
$("body").eoTextSearch("foo").filter(function () {
return $(this).closest("tr").is(":visible");
});
To remove unwanted elements from the search result. No "recounting the array length" necessary. Or you use each() directly and decide within what to do.

I cannot entirely get my head around your code, but the most likely issue is that you are removing items from the array, but not shrinking the array afterwards. Simply removing items will return you "undefined", and will not collapse the array.
I would suggest that you do one of the following:
Copy the array to a new array, but only copying those items that are not undefined
Only use those array items that are not undefined.
I hope this is something of a help.

Found the answer in another post.
Remove empty elements from an array in Javascript
Ended up using the answer's second option and it worked alright.

Simpler way to format if statement?

I have an if statement:
if(firstString == "no" && secondString == "no" && thirdString == "no"){
// Do stuff here
}
Is there a prettier way to format this? Using false instead of "no" is not an option, since the data I'm checking is from an AJAX request and I don't control its output. Otherwise I'd write it this way:
if(!firstString && !secondString && !thirdString){
// Do stuff here
}
Thanks
UPDATE:
I know this is totally ridiculous, but it occurred to me that this might actually be the shortest way:
if(firstString + secondString + thirdString == "nonono"){
// Do stuff here
}

Given that the number of strings is known in advance, then you have 2 options as far as I can see..
Leave it as it is. The if statement isn't hard to read, and any alternate formats will either be as complicated or more complicated.
convert the strings to booleans when you retrieve the data from the AJAX request, so that you're storing TRUE or FALSE instead of "yes" and "no". That would allow you to use a your preferred if statement format, and might be more efficient than many string comparisons if you do a lot of them.
In the end, which you do is up to you, but personally I think it would be better to just stick with what you've got. Don't worry about formatting an if statement, it's pretty obvious what it does, and in my opinion doesn't need to change.

If( "no" == firstString && firstString == secondString && secondString == thirdString )

It was a little difficult to determine exactly what you are evaluating to true or false, but this can be tweaked a tad to get what you're looking for.
var checkStrings = function() {
var no = "no",
args = Array.prototype.slice.call(arguments);
for (var i = 0, len = args.length; i < len; i++) {
if (args[i] !== no) {
return false;
}
}
return true;
};
if (checkStrings(firstString, secondString, thirdString)) {
// Do stuff here
}

Sorry, wasn't thinking--this is if you were checking whether ANY were 'no'
if ($.inArray('no', [firstString, secondString, thirdString]) >= 0) {
// Do something if the value is 'no'
}
UPDATED ANSWER
Unfortunately, jQuery doesn't have the reduce() function (another Array extra introduced in JS 1.6, but not available in older browsers) which would do the trick nicely.
Here's one way to check if all are 'no':
var found = true;
$.each([firstString, secondString, thirdString], function (i, str) {
if (str !== 'no') {
found = false;
}
});
It may seem uglier, but it should be shorter if you have a lot more strings to check.
If you want it wrapped in a function you could do:
function allTrue (arr, checkStr) {
var found = true;
$.each(arr, function (i, str) {
if (str !== checkStr) {
found = false;
}
});
return found;
}
if (allTrue([firstString, secondString, thirdString], 'no')) {
// ...
}

function F(var value){
return value === "no";
}
if(F(firstString) && F(secondString) && F(thirdString)){
// Do stuff here
}

Another option, using jQuery.unique:
var uniques = $.unique([firstString, secondString, thirdString]);
if (uniques.length === 1 && uniques[0] === "no") {
// do stuff
}