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JavaScript - What is wrong with my Hash Table?

I am doing the first problem on LeetCode, Two Sum. I am trying to do the problem using a hash table. This is what I came up with:
var twoSum = function(nums, target) {
var hash = [];
for(var i = 0; i < nums.length; i++) {
var need = target - nums[i];
if (!hash[need]) {
hash[need] = i;
} else {
return [hash[nums[i]], i];
}
}
};
When I run my code, I am getting undefined as an answer. Let's say I have an array [2,3,1,6,4] and my target is 8. When I iterated through the array, I will get 8-2=6, 8-3=5, 8-1=7, 8-6=2, and 8-4=4. So, my hash table should look like this according to my code:
6:0
5:1
7:2
2:3
4:4
If something is not in the hash table, I want to throw it into the hash. When I run into the number in the hash, then I return hash[nums[i]] and i since I am ready at the index and hash[nums[i]] has the value of the index that I need. I am unsure why I am getting an undefined. Any advice to make this better?

Please see the code. I have removed the else part and returned the hash at end. Please let me know if this is what you were looking.
var twoSum = function(nums, target) {
var hash = [];
for(var i = 0; i < nums.length; i++) {
var need = target - nums[i];
if (!hash[need]) {
hash[need] = i;
}
}
return hash;
};
console.log(twoSum([2,3,1,6,4],8))

Check for duplicates in array with randomly generated values

I'm working on exercism question and am stuck on one of the jasmine-node based tests, which says that I should be able to generate 10000 random names without any clashes (e.g. 2 randomly generated names match). This is the test:
it('there can be lots of robots with different names each', function() {
var i,
numRobots = 10000,
usedNames = {};
for (i = 0; i < numRobots; i++) {
var newRobot = new Robot();
usedNames[newRobot.name] = true;
}
expect(Object.keys(usedNames).length).toEqual(numRobots);
});
What I think I need to do is:
Create an array to hold all the names (robotNames),
Each time a name is generated, check if it exists in the array,
If it does, generate another name,
If it doesn't, add it to the array.
And here is my code so far...
"use strict";
var robotNames = [];
var name;
var Robot = function() {
this.name = this.generateName();
};
Robot.prototype.generateName = function() {
var letters = "";
var alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
var numbers = "";
var digits = "0123456789";
// generate random characters for robot name...
for( var i=0; i < 2; i++ ) {
letters += alphabet.charAt(Math.floor(Math.random() * alphabet.length));
};
for( var i=0; i < 3; i++ ) {
numbers += digits.charAt(Math.floor(Math.random() * digits.length));
};
name = letters+numbers;
// Loop through array to check for duplicates
for(var i = 0; i < robotNames.length; i++) {
if (name == robotNames[i]) {
this.generateName();
return;
} else {
robotNames.push(name);
}
}
return name;
};
Robot.prototype.reset = function() {
this.name = this.generateName();
};
module.exports = Robot;
The test fails with an error message: "Expected 9924 to equal 10000."
The '9924' number is slightly different each time I run the test. I'm thinking this means the generateName function is eventually generating 2 matching random names. It seems as though my loop for checking duplicates is not being run and I'm not sure why.
I have tried a couple of different versions of the loop but with no success. So my questions is a) is my approach correct and there is something wrong with the syntax of my loop? or b) have I got the wrong idea about how to check for duplicates here?
Any pointers appreciated, thanks.

The problem is in this bit:
for(var i = 0; i < robotNames.length; i++) {
if (name == robotNames[i]) {
this.generateName();
return;
} else {
robotNames.push(name);
}
}
...you probably only want to push your name if NONE of the names fail to match. Here you're adding it to the list as soon as you find ONE that doesn't match. You want something more like:
for(var i = 0; i < robotNames.length; i++) {
if (name == robotNames[i]) {
return this.generateName();
}
}
robotNames.push(name);
(actually, combined with the fact that you weren't even returning the recursive call to this.generateName(), I'm not sure how your program could work...)

Find a library with an implementation for Sets. Collections.js is a good example.
One property of a set is that it doesn't have duplicates. So when you add a value to a set it will look for a duplicate and then add the value if no duplicate exists.

Pull data from one Google spreadsheet to another using Google script

I have 2 spreadsheet in my Drive. I want to pull data from a cell in 1 spreadsheet and copy it in another.
The spreadsheet "TestUsage" will sometimes have data in column A, but none is column B.
I would like so that when I open the spreadsheet, it would populate that empty cell in sheet "TestUsage" from sheet "TestParts".
Here is my code:
var ssTestUsage = SpreadsheetApp.getActiveSpreadsheet();
var sTestUsage = ssTestUsage.getActiveSheet();
var lastRowTestUsage = sTestUsage.getLastRow();
var rangeTestUsage = sTestUsage.getSheetValues(1, 1, lastRowTestUsage, 4);
var TESTPARTS_ID = "1NjaFo0Y_MR2uvwit1WuNeRfc7JCOyukaKZhuraWNmKo";
var ssTestParts = SpreadsheetApp.openById(TESTPARTS_ID);
var sTestParts = ssTestParts.getSheets()[0];
var lastRowTestParts = sTestParts.getLastRow();
var rangeTestParts = sTestParts.getSheetValues(1, 1, lastRowTestParts, 3);
function onOpen() {
for (i = 2; i < lastRowTestUsage; i++) {
if (rangeTestUsage[i][0] !== "" && rangeTestUsage[i][1] == "") {
for (j = 1; j < lastRowTestParts; j++) {
if (rangeTestUsage[i][0] == rangeTestParts[j][0]) {
Logger.log(rangeTestUsage[i][1]);
Logger.log(rangeTestParts[j][1]);
rangeTestUsage[i][1] = rangeTestParts[j][1];
break;
}
}
}
}
}
The problem with this is this doesn't do anything:
rangeTestUsage[i][1] = rangeTestParts[j][1];
I know there must be a method that can get data from one range to another.
Please let me know if I am totally incorrect or I am on the right path.

the statement
"this doesn't do anything:"
rangeTestUsage[i][1] = rangeTestParts[j][2];
is not really true... and not really false neither..., actually it does assign the value to rangeTestUsagei but you dont see it because it is not reflected in the spreadsheet.
Both values are taken from the Sheet using getValues so at that time they are both array elements.
What is missing is just writing back the array to the sheet using the symetrical statement setValues()
Give it a try and don't hesitate to come back if something goes wrong.
EDIT :
I didn't notice at first that you were using getSheetValues instead of getValues (simply because I never use this one)... the only difference is that getValues is a method of the range class while yours belongs to the sheet class; the syntax is similar in a way, just use
Sheet.getRange(row,col,width,height).getValues()
it takes one word more but has the advantage to have a direct equivalent to set values
Sheet.getRange(row,col,width,height).setValues()

Serge insas has a good explanation of why your code doesn't work and hints at the solution below.
I recommend you use an array to store the updated values of column B that you want then set the entire column at the end.
Modifying your code...
var ssTestUsage = SpreadsheetApp.getActiveSpreadsheet();
var sTestUsage = ssTestUsage.getActiveSheet();
var lastRowTestUsage = sTestUsage.getLastRow();
var rangeTestUsage = sTestUsage.getSheetValues(1, 1, lastRowTestUsage, 2);
var TESTPARTS_ID = "1NjaFo0Y_MR2uvwit1WuNeRfc7JCOyukaKZhuraWNmKo";
var ssTestParts = SpreadsheetApp.openById(TESTPARTS_ID);
var sTestParts = ssTestParts.getSheets()[0];
var lastRowTestParts = sTestParts.getLastRow();
var rangeTestParts = sTestParts.getSheetValues(1, 1, lastRowTestParts, 2);
var colB = [];
function onOpen() {
for (i = 2; i < lastRowTestUsage; i++) {
if (rangeTestUsage[i][0] !== "" && rangeTestUsage[i][1] == "") {
var matched = false;
for (j = 1; j < lastRowTestParts; j++) {
if (rangeTestUsage[i][0] == rangeTestParts[j][0]) {
//Logger.log(rangeTestUsage[i][1]);
//Logger.log(rangeTestParts[j][1]);
colB.push([rangeTestParts[j][1]]); // push the value we want into colB array
matched = true;
break;
}
}
if(!matched) // this is in case you don't have a match
colB.push([""]); // incase we don't have a matching part
} else {
colB.push([rangeTestUsage[i][0]]); // we already have a value we want so just add that to colB array
}
}
sTestUsage.getRange(2,2,lastRowTestUsage).setValues(colB); // update entire column b with values in colB array
}

Javascript: matching a dynamic string against an array

I'm attempting to teach myself javascript. I chose something I assumed was simple, but ran into problems relatively quickly.
I'm attempting to search a string for another string given by the user.
My code so far is:
var source = "XREs2qqAQfjr6NZs6H5wkZdOES5mikexRkOPsj6grQiYNZfFoqXI4Nnc1iONKVrA";
var searchString = []; //the users input
searchString = prompt("Enter search string");
var hits = [];
var one = 0;
var two = 0;
var k = 0;
var sourceSearch = function(text) {
for(i = 0; i < source.length; i++) { //for each character in the source
if(source[i] === searchString[0]) { //if a character in source matches the first element in the users input
one = source.indexOf(i); //confused from here on
for(p = searchString.length; p > 0; p--) {
}
}
}
};
sourceSearch(searchString);
My idea was:
check to see if the first loop finds a character that matches the first character in the user input
if it matches, check to see if the next X characters after the first match the next X characters in the source string
if they all match, push them to the hits array
My problem: I have no idea how to iterate along the arrays without nesting quite a few if statements, and even then, that wouldn't be sufficient, considering I want the program to work with any input.
Any ideas would be helpful. Thanks very much in advance.
Note: There are a few un-used variables from ideas I was testing, but I couldn't make them work.

You can try:
if (source.indexOf(searchString) !== -1) {
// Match!
}
else
{
//No Match!
}

As the other answers so far point out, JavaScript strings have an indexOf function that does what you want. If you want to see how it's done "by hand", you can modify your function like this:
var sourceSearch = function(text) {
var i, j, ok; // always declare your local variables. globals are evil!
// for each start position
for(i = 0; i < source.length; i++) {
ok = true;
// check for a match
for (j = searchString.length - 1; ok && j >= 0; --j) {
ok = source[i + j] === searchString[j];
}
if (ok) {
// searchString found starting at index i in source
}
}
};
This function will find all positions in source at which searchString was found. (Of course, you could break out of the loop on the first success.) The logic is to use the outer loop to advance to each candidate start position in source and use the inner loop to test whether that position actually is the position of a match to searchString.
This is not the best algorithm for searching strings. The built-in algorithm is much faster (both because it is a better algorithm and because it is native code).

to follow your approach, you can just play with 2 indexes:
var sourceSearch = function(text) {
j = 0;
for(i = 0; i < source.length; i++) {
if(source[i] === text[j]) {
j++;
} else {
j = 0;
}
if (j == text.length) {
console.log(i - j); //this prints the starting index of the matching substring
}
}
};

These answers are all pretty good, but I'd probably opt for something like this:
var source = "XREs2qqAQfjr6NZs6H5wkZdOES5mikexRkOPsj6grQiYNZfFoqXI4Nnc1iONKVrA";
var searchString = []; //the users input
searchString = prompt("Enter search string");
var hits = source.split(searchString);
var hitsCount = hits.length - 1;
This way you have all of the data you need to figure out where each hit occurred in he source, if that's important to you.

Finding an object and returning it based on search criteria

I have been searching online all day and I cant seem to find my answer. (and I know that there must be a way to do this in javascript).
Basically, I want to be able to search through an array of objects and return the object that has the information I need.
Example:
Each time someone connects to a server:
var new_client = new client_connection_info(client_connect.id, client_connect.remoteAddress, 1);
function client_connection_info ( socket_id, ip_address, client_status) {
this.socket_id=socket_id;
this.ip_address=ip_address;
this.client_status=client_status; // 0 = offline 1 = online
};
Now, I want to be able to search for "client_connection.id" or "ip_address", and bring up that object and be able to use it. Example:
var results = SomeFunction(ip_address, object_to_search);
print_to_screen(results.socket_id);
I am new to javascript, and this would help me dearly!

Sounds like you simply want a selector method, assuming I understood your problem correctly:
function where(array, predicate)
{
var matches = [];
for(var j = 0; j < array.length; j++)
if(predicate(j))
matches.push(j);
return matches;
}
Then you could simply call it like so:
var sample = [];
for(var j = 0; j < 10; j++)
sample.push(j);
var evenNumbers = where(sample, function(elem)
{
return elem % 2 == 0;
});
If you wanted to find a specific item:
var specificguy = 6;
var sixNumber = where(sample, function(elem)
{
return elem == specificguy;
});

What have you tried? Have you looked into converting the data from JSON and looking it up as you would in a dictionary? (in case you don't know, that would look like object['ip_address'])
jQuery has a function for this jQuery.parseJSON(object).

You're going to need to loop through your array, and stop when you find the object you want.
var arr = [new_client, new_client2, new_client3]; // array of objects
var found; // variable to store the found object
var search = '127.0.0.1'; // what we are looking for
for(var i = 0, len = arr.length; i < len; i++){ // loop through array
var x = arr[i]; // get current object
if(x.ip_address === search){ // does this object contain what we want?
found = x; // store the object
break; // stop looping, we've found it
}
}