Develop Reference

How can I extract the numbers from a string and store them into variables?

I have a string containing numbers, I need to extract the numbers from the string and store them into variables. For example, if my user input is:
"make a C++ program that adds 2 numbers together"
Then I need to extract the 2 and store it in a variable.
I tried this:
function hasNumbers(t)
{
var regex = /\d/g;
return regex.test(t);
}
Something like this would be good but I'd prefer it not to be a function.
Either something like var amountOfVariables = or if(userInput.includes,isinteger,typeof, etc.
There has to be a combination of methods that allows you to find a integer in a string & then store it in a variable, right?
I was trying to use document.write(amountOfVariables);
to test if it was being stored but no luck. I know I need to convert the String part into an int.
I want a method or a way to store integers in a users input in variables for later use in functions. But at the moment I can't get this to work.

If I'm not mistaken, the question requires "contains number", not "is number". So:
function hasNumber(myString) {
return /\d/.test(myString);
}

I found a way. not sure if i can use this to find more then 1 number in a string though
const [amountOfVariables] = userInput.match(/\d+/g) || [NaN];
parseInt(amountOfVariables)
document.write(amountOfVariables);
This searches the string for a number then stores it in a variable

HashMap example in pure JavaScript

I have String like below.
10=150~Jude|120~John|100~Paul#20=150~Jude|440~Niroshan#15=111~Eminem|2123~Sarah
I need a way to retrieve the string by giving the ID.
E.g.: I give 20; return 150~Jude|440~Niroshan.
I think I need a HashMap to achieve this.
Key > 20
Value > 150~Jude|440~Niroshan
I am looking for an pure JavaScript approach. Any Help greatly appreciated.

If you're getting the above string in response from server, it'll be better if you can get it in the below object format in the JSON format. If you don't have control on how you're getting response you can use string and array methods to convert the string to object.
Creating an object is better choice in your case.
Split the string by # symbol
Loop over all the substrings from splitted array
In each iteration, again split the string by = symbol to get the key and value
Add key-value pair in the object
To get the value from object using key use array subscript notation e.g. myObj[name]
var str = '10=150~Jude|120~John|100~Paul#20=150~Jude|440~Niroshan#15=111~Eminem|2123~Sarah';
var hashMap = {}; // Declare empty object
// Split by # symbol and iterate over each item from array
str.split('#').forEach(function(e) {
var arr = e.split('=');
hashMap[arr[0]] = arr[1]; // Add key value in the object
});
console.log(hashMap);
document.write(hashMap[20]); // To access the value using key

If you have access to ES6 features, you might consider using Map built-in object, which will give you helpful methods to retrieve/set/... entries (etc.) out-of-the-box.

producing a word from a string in javascript

I have a string which is name=noazet difficulty=easy and I want to produce the two words noazet and easy. How can I do this in JavaScript?
I tried var s = word.split("=");
but it doesn't give me what I want .

In this case, you can do it with that split:
var s = "name=noazet difficulty=easy";
var arr = s.split('=');
var name = arr[0]; //= "name"
var easy = arr[2]; //= "easy"
here, s.split('=') returns an array:
["name","noazet difficulty","easy"]

you can try following code:
word.split(' ').map(function(part){return part.split('=')[1];});
it will return an array of two elements, first of which is name ("noazet") and second is difficulty ("easy"):
["noazet", "easy"]

word.split("=") will give you an array of strings which are created by cutting the input along the "=" character, in your case:
results = [name,noazet,difficulty,easy]
if you want to access noazet and easy, these are indices 1 and 3, ie.
results[1] //which is "noazet"
(EDIT: if you have a space in your input, as it just appeared in your edit, then you need to split by an empty string first - " ")
Based on your data structure, I'd expect the desired data to be always available in the odd numbered indices - but first of all I'd advise using a different data representation. Where is this string word coming from, user input?

Just as an aside, a better idea than making an array out of your input might be to map it into an object. For example:
var s = "name=noazet difficulty=easy";
var obj = s.split(" ").reduce(function(c,n) {
var a = n.split("=");
c[a[0]] = a[1];
return c;
}, {});
This will give you an object that looks like this:
{
name: "noazert",
difficulty: "easy"
}
Which makes getting the right values really easy:
var difficulty = obj.difficulty; // or obj["difficulty"];
And this is more robust since you don't need to hard code array indexes or worry about what happens if you set an input string where the keys are reversed, for example:
var s = "difficulty=easy name=noazet";
Will produce an equivalent object, but would break your code if you hard coded array indexes.

You may be able to get away with splitting it twice: first on spaces, then on equals signs. This would be one way to do that:
function parsePairs(s) {
return s.split(' ').reduce(
function (dict, pair) {
var parts = pair.split('=');
dict[parts[0]] = parts.slice(1).join('=');
return dict;
},
{}
);
}
This gets you an object with keys equal to the first part of each pair (before the =), and values equal to the second part of each pair (after the =). If a string has multiple equal signs, only the first one is used to obtain the key; the rest become part of the value. For your example, it returns {"name":"noazet", "difficulty":"hard"}. From there, getting the values is easy.
The magic happens in the Array.prototype.reduce callback. We've used String.prototype.split to get each name=value pair already, so we split that on equal signs. The first string from the split becomes the key, and then we join the rest of the parts with an = sign. That way, everything after the first = gets included in the value; if we didn't do that, then an = in the value would get cut off, as would everything after it.
Depending on the browsers you need to support, you may have to polyfill Array.prototype.reduce, but polyfills for that are everywhere.

Sending an array with JavaScript to the next page

The combination of my methods of declaring an array, adding elements to the array and applying the method toString() does not work. Essentially I enter a certain number (between one and five) values to textvariables : fontVorto1, fontVorto2, fontVorto3 ……… in the html-part of the document.
When I decide on leaving the remaining textelements empty, I click on a button, to assign them to an array, by way of the following function:
function difinNombroFv () {
var fontVortoj = new array();
fontVortoj[0] = document.getElementsByName("fontVorto1")[0].value;
fontVortoj[1] = document.getElementsByName("fontVorto2")[0].value;
fontVortoj[2] = document.getElementsByName("fontVorto3")[0].value;
……………….
and put them together in a string:
x = fontVortoj.toString();
document.getElementsByName("fontVorto")[0].value = x;
(the extra variable x is not needed) to enable me sending them to the next document, where I want to unserialize them with
$fontVortoj = unserialize($_POST["fontVorto"]);
I tested the method toString() by insering an alert(x), but the result was that I got for x the value of "fontVorto1" only.
I met solutions with JSON, jQuery etc., but I never used those "languages", only HTML, JavaScript, PHP.
Will my Christmas day be spoiled because of this simple problem ;>)?

couple of things to note:
1. var fontVortoj = new array(); . here new array() is not correct. it should be:
var fontVortoj = new Array();
now if you call fontVortoj.toString(), then it will convert the array and return a string with array elements separated by comma.
you can rebuild the array from the string in php by using "explode" function.
you can rebuild the array from the string in javascript by using "split" function.

Apparently I misunderstood the question to begin with.
To serialize an astray, you can use .join()
By default, it will give you the values, joined by commas.
To deserialize, use .split()
If there's a chance that there might be commas in your values, choose a more elaborate string for joining:
var ar = ["a", "b"];
var serialized = ar.join("|"); // "a|b"
var deserialized = serialized.split("|"); //["a", "b"]
The string that you use for joining and splitting can be as long as you like.
If you want to be completely covered against any values, then you need to look at JSON.stringify() & JSON.parse(). But that had browser compatibility issues.

optimize search through large js string array?

if I have a large javascript string array that has over 10,000 elements,
how do I quickly search through it?
Right now I have a javascript string array that stores the description of a job,
and I"m allowing the user to dynamic filter the returned list as they type into an input box.
So say I have an string array like so:
var descArr = {"flipping burgers", "pumping gas", "delivering mail"};
and the user wants to search for: "p"
How would I be able to search a string array that has 10000+ descriptions in it quickly?
Obviously I can't sort the description array since they're descriptions, so binary search is out. And since the user can search by "p" or "pi" or any combination of letters, this partial search means that I can't use associative arrays (i.e. searchDescArray["pumping gas"] )
to speed up the search.
Any ideas anyone?

As regular expression engines in actual browsers are going nuts in terms of speed, how about doing it that way? Instead of an array pass a gigantic string and separate the words with an identifer.
Example:
String "flipping burgers""pumping gas""delivering mail"
Regex: "([^"]*ping[^"]*)"
With the switch /g for global you get all the matches. Make sure the user does not search for your string separator.
You can even add an id into the string with something like:
String "11 flipping burgers""12 pumping gas""13 delivering mail"
Regex: "(\d+) ([^"]*ping[^"]*)"
Example: http://jsfiddle.net/RnabN/4/ (30000 strings, limit results to 100)

There's no way to speed up an initial array lookup without making some changes. You can speed up consequtive lookups by caching results and mapping them to patterns dynamically.
1.) Adjust your data format. This makes initial lookups somewhat speedier. Basically, you precache.
var data = {
a : ['Ant farm', 'Ant massage parlor'],
b : ['Bat farm', 'Bat massage parlor']
// etc
}
2.) Setup cache mechanics.
var searchFor = function(str, list, caseSensitive, reduce){
str = str.replace(/(?:^\s*|\s*$)/g, ''); // trim whitespace
var found = [];
var reg = new RegExp('^\\s?'+str, 'g' + caseSensitive ? '':'i');
var i = list.length;
while(i--){
if(reg.test(list[i])) found.push(list[i]);
reduce && list.splice(i, 1);
}
}
var lookUp = function(str, caseSensitive){
str = str.replace(/(?:^\s*|\s*$)/g, ''); // trim whitespace
if(data[str]) return cache[str];
var firstChar = caseSensitive ? str[0] : str[0].toLowerCase();
var list = data[firstChar];
if(!list) return (data[str] = []);
// we cache on data since it's already a caching object.
return (data[str] = searchFor(str, list, caseSensitive));
}
3.) Use the following script to create a precache object. I suggest you run this once and use JSON.stringify to create a static cache object. (or do this on the backend)
// we need lookUp function from above, this might take a while
var preCache = function(arr){
var chars = "abcdefghijklmnopqrstuvwxyz".split('');
var cache = {};
var i = chars.length;
while(i--){
// reduce is true, so we're destroying the original list here.
cache[chars[i]] = searchFor(chars[i], arr, false, true);
}
return cache;
}
Probably a bit more code then you expected, but optimalisation and performance doesn't come for free.

This may not be an answer for you, as I'm making some assumptions about your setup, but if you have server side code and a database, you'd be far better off making an AJAX call back to get the cut down list of results, and using a database to do the filtering (as they're very good at this sort of thing).
As well as the database benefit, you'd also benefit from not outputting this much data (10000 variables) to a web based front end - if you only return those you require, then you'll save a fair bit of bandwidth.

I can't reproduce the problem, I created a naive implementation, and most browsers do the search across 10000 15 char strings in a single digit number of milliseconds. I can't test in IE6, but I wouldn't believe it to more than 100 times slower than the fastest browsers, which would still be virtually instant.
Try it yourself: http://ebusiness.hopto.org/test/stacktest8.htm (Note that the creation time is not relevant to the issue, that is just there to get some data to work on.)
One thing you could do wrong is trying to render all results, that would be quite a huge job when the user has only entered a single letter, or a common letter combination.

I suggest trying a ready made JS function, for example the autocomplete from jQuery. It's fast and it has many options to configure.
Check out the jQuery autocomplete demo

Using a Set for large datasets (1M+) is around 3500 times faster than Array .includes()
You must use a Set if you want speed.
I just wrote a node script that needs to look up a string in a 1.3M array.
Using Array's .includes for 10K lookups:
39.27 seconds
Using Set .has for 10K lookups:
0.01084 seconds
Use a Set.