Develop Reference

Finding the index of several identical words

I have a laTeX string like this
let result = "\\frac{x}{2}+\\frac{3}{x}";
I want to find the index of "frac"s in the string and put them in a array then I want to find the first '}' char after "frac" and replace it with "}/" and finally remove "frac" from the string.
I used this block of code but it just work correctly when we have one "frac"
let result = "\\frac{x}{2}+\\frac{3}{x}";
if (result.indexOf("frac") != -1) {
for (let i = 0; i < result.split("frac").length; i++) {
let j = result.indexOf("frac");
let permission = true;
while (permission) {
if (result[j] == "}") {
result = result.replace(result[j], "}/")
permission = false;
}
j++;
}
result = result.replace('frac', '');
}
}
console.log(result)
OUTPUT: \\{x}//{2}+\\{3}{x}
Could anyone help me to improve my code?

Something like this?
frac(.+?)}
is the literal frac followed by a capture group that will capture one or more of anything .+ until a } and replace it with that anything plus a }/
Using the function replacement to grab index and replace
let result = "\\frac{x}{2}+\\frac{3}{x}";
let pos = [];
const newRes = result.replace(/frac(.+?)}/g,function(match, found, offset,string) {
console.log(match,found,offset,string)
pos.push(offset)
return `${found}/`; // return the found string with the added slash
})
console.log(pos)
console.log(newRes)
Older answer using two sets of code
let result = "\\frac{x}{2}+\\frac{3}{x}";
let re = /frac/gi, res, pos = [];
while ((res = re.exec(result))) {
pos.push(res.index);
}
const newRes = result.replace(/frac(.+?)}/g,"$1}/")
console.log(pos)
console.log(newRes)

How to creat a dynamic RegEx

I'm trying to match some words in a string. But I don't have a predefined number of words I need to find.
For example I search for Ubuntu 18 10 in ubuntu-18.10-desktop-amd64.iso.torrent would return true.
Or I could search for centos 7 in CentOS-7-x86_64-LiveGNOME-1804.torrent would also return true.
I don't need to check if it's lowercase or not.
What I tried :
$.get('interdit', function(data) {
var lines = data.split("\n");
$.each(lines, function(n, data_interdit) {
var url_check = $('textarea#url').val()
var split_forbidden = data_interdit.split(/[\s|,|_|.|-|:]+/);
var exist = 0;
$.each(split_forbidden, function(n, data) {
var n = url_check.search("^("+ data +")");
if(n != -1){
exist = 1
}else{
exist = 0
}
console.log('Forbidden: '+ data + ' Result: ' + n);
})
if(exist == 1){
console.log('found')
}
});
});
Sample data of the file interdit :
CentOS.7
Ubuntu-18

You want to look for existing words within the input string without the order being taken into account. You need to use positive lookaheads for this:
var search = 'Ubuntu 18 10';
var str = 'ubuntu-18.10-desktop-amd64.iso.torrent';
var re = new RegExp('^(?=.*' + search.split(/[\s,_.:-]+/).join(')(?=.*') + ')', 'i')
console.log(re.test(str));
This produces a regex as the following (with i flag set):
^(?=.*Ubuntu)(?=.*18)(?=.*10)

RegEx Array
Update
"The code give me an error jsbin.com/pecoleweyi/2/edit?js,console"
Although the question did not include unlikely input such as: *centos 7*, add the following line to escape the special characters that occur in input:
var esc = word.replace(/[.*+?^${}()|[\]\\]/gi, '\\$&');
and change the next line:
var sub = esc.replace(/\s/gi, '.');
The demo below will:
accept a string (str) to search and an array of strings (tgt) to find within the string,
.map() the array (tgt) which will run a function on each string (word)
escape any special characters:
var esc = word.replace(/[.*+?^${}()|[\]\\]/gi, '\\$&');
replace any spaces (/\s/g) with a dot (.):
var sub = esc.replace(/\s/g, '.');
then makes a RegExp() Object so a variable can be inserted in the pattern via template literal interpolation (say that ten times fast):
var rgx = new RegExp(`${sub}`, `gim`);
uses .test() to get a boolean: found = true / not found = false
var bool = rgx.test(str);
create an Object to assign the search string: word as a property and the boolean: bool as it's value.
var obj = {
[word]: bool
};
returns an array of objects:
[{"centos 7":true},{"Ubuntu 18 10":true}]
Demo
var str = `ubuntu-18.10-desktop-amd64.iso.torrent
CentOS-7-x86_64-LiveGNOME-1804.torrent`;
var tgt = [`centos 7`, `Ubuntu 18 10`, `corn flakes`, `gnome`, `Red Hat`, `*centos 7*`];
function rgxArray(str, tgt) {
var res = tgt.map(function(word) {
var esc = word.replace(/[.*+?^${}()|[\]\\]/gi, '\\$&');
var sub = esc.replace(/\s/gi, '.');
var rgx = new RegExp(`${sub}`, `gi`);
var bool = rgx.test(str);
var obj = {
[word]: bool
};
return obj;
});
return res;
}
console.log(JSON.stringify(rgxArray(str, tgt)));

How to check if part of a string is in an array?

user_input = "";
answer = "";
Array.greeting = ["hi", "hello"]
Array.names = ["john","james"]
user_input = document.getElementById('user_input').value.toLowerCase();
document.getElementById('text_input').innerHTML = user_input;
documnet.getElementById('say_something').innerHTML = say;
if(""){}
else{}
if(Array.greeting.includes(user_input) > 0){
say = "Hello";
}
if(Array.names.includes(user_input) > 0){
say = "User";
}
This is what i understand and have got up and running with correct outputs but how could i use input "hi john" and get output of "Hello User" with out baking it into an array?

You could do it like this:
var greetings = ["hi", "hello"];
var names = ["john","james"];
submit.onclick = function () {
// Split input into words, and convert that array to a Set for fast lookup
var words = new Set(user_input.value.split(/\s+/));
// Choose a greeting that is not among the input words.
// If all of them occur in the input, take the first greeting word
var greeting = greetings.find( greeting => !words.has(greeting)) || greetings[0];
// Choose a name that is not among the input words (or take the first)
var name = names.find( name => !words.has(name)) || names[0];
// Output with textContent (not innerHTML!)
text_input.textContent = user_input.value;
say_something.textContent = greeting + ' ' + name;
}
Input: <input id="user_input"><button id="submit">Submit</button><br>
You said: <span id="text_input"></span><br>
Reply: <span id="say_something"></span>
Obviously, when you enter both "hi" and "hello", the code will not find a greeting to use. In that case it uses the first greeting in the array ("hi"). The same principle applies for the names.

Let's simplify your requirement as:
You want to check if any element of an array "arr" contains part of string "s".
var check = function(arr, s) {
for (var i = 0; i < arr.length; i++) {
if (s.indexOf(arr[i]) > -1) {
return true;
}
}
return false;
}

Extract Keywords from String: Javascript

Lets consider i have a string & want to extract uncommon keywords for SEO. $text = "This is some text. This is some text. Vending Machines are great.";
& Will define a array of common words to ignore keywords in extracted list like $commonWords = ['i','a','about','an','and','are','as','at','be','by','com','de','en','for','from','how','in','is','it','la','of','on','or','that','the','this','to','was','what','when','where','who','will','with','und','the','www'];
Expected output: Result=[some,text,machines,vending]
Would really appreciate if Could any one help us to write generic logic or procedure for the extracting keywords from string?

This can help ( it supports multi languages):
https://github.com/michaeldelorenzo/keyword-extractor
var sentence = "President Obama woke up Monday facing a Congressional defeat that many in both parties believed could hobble his presidency."
// Extract the keywords
var extraction_result = keyword_extractor.extract(sentence,{
language:"english",
remove_digits: true,
return_changed_case:true,
remove_duplicates: false
});

Some like this
var $commonWords = ['i','a','about','an','and','are','as','at','be','by','com','de','en','for','from','how','in','is','it','la','of','on','or','that','the','this','to','was','what','when','where','who','will','with','und','the','www'];
var $text = "This is some text. This is some text. Vending Machines are great.";
// Convert to lowercase
$text = $text.toLowerCase();
// replace unnesessary chars. leave only chars, numbers and space
$text = $text.replace(/[^\w\d ]/g, '');
var result = $text.split(' ');
// remove $commonWords
result = result.filter(function (word) {
return $commonWords.indexOf(word) === -1;
});
// Unique words
result = result.unique();
console.log(result);

var string = "This is some text. This is some text. Vending Machines are great.";
var substrings = ['your','words', 'here'],
var results = array();
for (var i = substrings.length - 1; i >= 0; --i) {
if (string.indexOf(substrings[i]) != -1) {
// str contains substrings[i]
array.push(substrings[i]);
}
}

var arrayLength = commonWords.length;
var words = []; //new array to say the words
for (var i = 0; i < arrayLength; i++) {
if ($text.indexOf(commonWords[i]) > -1){
words.push(commonWords[i]);
}
}

Print out last character of all words in a string

What are some clean ways to print out last characters of all words in a string. For example, a phrase like "laugh ride lol hall bozo " --> "hello" and "dog polo boo sudd noob smiley ride " --> goodbye.
These lines would return "1" and undefined. Any help is much appreciated.
var decrypt = function (message) {
var solution = [];
for (var i = 0; i < message.length; i++) {
if(message.charAt(i)===" ") {
return solution.push(message.charAt(i-1));
};
};
};
var resulta = decrypt("laugh ride lol hall bozo ")
console.log(resulta); // logs "hello"
var resultb = decrypt("dog polo boo sudd noob smiley ride ")
console.log(resultb); // logs "goodbye"

Don't return inside the loop, just append the charater to the result. When the loop is done, return what you want. Since you apparently want to return a string, you don't need an array.
var decrypt = function (message) {
var solution = '';
for (var i = 0; i < message.length; i++) {
if(message.charAt(i)===" ") {
solution += message.charAt(i-1);
};
};
return solution;
};
var resulta = decrypt("laugh ride lol hall bozo ")
console.log(resulta); // logs "hello"
var resultb = decrypt("dog polo boo sudd noob smiley ride ")
console.log(resultb); // logs "goodbye"

Assuming the words are separated by spaces you can do it in one line:
var decrypt = function (message) {
return (message+" ").match(/\w\s/g).join("").replace(/\s/g,"");
}
The regex /\w\s/g will match a word character followed by a space. The .match() method will return an array of all such matches. .join() will join the array elements into a string. And then .replace() will remove the spaces from that string.
Note that I'm using (message+" ") to add an extra space to the input string just in case it doesn't already have one at the end.
Also the code I showed doesn't allow for strings that don't have any "word characters" in them. If you want to test for that you need two lines:
var decrypt = function (message) {
var m = (message+" ").match(/\w\s/g);
return m ? m.join("").replace(/\s/g,"") : "";
//include default value for non match here^^
}

Another clean solution is
var decrypt = function (message) {
return message.split(' ')
.map(function(word) { return word.slice(-1); })
.join('');
}
This is relies on Array.prototype.map, which was added in ES5 with support for all modern browsers (http://kangax.github.io/compat-table/es5/#Array.prototype.map).

Considering you only care about the last character of each word, I would loop through the string in reverse. This allows you to also print the last character in the string without appending a space on the end of the encoded message.
function decrypt(message) {
var c, secret = '', lastSpace = true;
for (var i = (message || '').length - 1; i >= 0; i--, lastSpace = c === ' ') {
c = message.charAt(i);
if (lastSpace) secret = c + secret;
}
return secret;
}