Can somebody please help me understand what is going on in Getcookie function. I am trying to get my in-depth understanding of whats happening in every single line of code.
function Getcookie(name) {
var dc = ";" + document.cookie
var start = dc.indexOf(";" + name + "=")
if(start == -1) return false
start += name.length + 2 // Why is 2 being added here
var end = dc.indexOf(";", start)
end = (end == -1) ? dc.length: end
return decodeURI(dc.substring(start, end));
}
The only real question I see is "Why is 2 being added here".
The document.cookie looks like this:
name1=value1;name2=value2;name3=value3...
If name = "name2", start will be the index of ;name2= in that string, and we want to get value2. To get from the beginning of that string to the end, we add the length of name2, and then an additional 2 for the ; and = characters. Now start points just past the = character, which is the beginning of the value.
After that, we search for the next ; character and set end to its index. If it's not found, we set it to dc.length (you have a typo there, dec should be dc). Then the value is everything from start to end.
Related
I wanted my passwords to include at least: 1 capital, 1 special character
I am trying with this while loop to meet the requirements. What am i doing wrong?
const characters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ#$!-_";
const capital = /ABCDEFGHIJKLMNOPQRSTUVWXYZ/;
const special = /#$!-_/;
function PWord (){
let pass = ""
while(!((capital.test(pass)) && (special.test(pass))) ){
for (i=0; i<=11; i++)
{
let rand_char = characters.charAt(Math.floor(Math.random()*characters.length));
pass = pass + rand_char;
}
return pass
}
}
for(let i=0;i<=3;i++){
let ps = PWord();
console.log("Password" + (i+1) + ":" + ps);
}
The main issue I see here is your use of return in the while loop. return will always end the execution of the entire function and return the specified value. The condition in your loop will only be checked once since you're returning before giving it the chance to check and run again. Try moving that line outside of the loop.
hi this is my first question, sorry if it is stupid but i stumble upon this code
function format(input){
var num = input.value.replace(/\./g,'');
if(!isNaN(num)){
num = num.toString().split('').reverse().join('').replace(/(?=\d*\.?)(\d{1})/g,'$1.');
num = num.split('').reverse().join('').replace(/^[\.]/,'');
input.value = num;
}
else{ alert('just numeric values please');
input.value = input.value.replace(/[^\d\.]*/g,'');
}
}
i don't really understand how it works, but basically it formats an input in real time to this format "9.9.9.9.9" but i want it to have it like this "9.9.9.9.9.". How can i add that last period?
thanks beforehand
If all you need to do is add the period to the end of the string, just do:
num + ".";
For your entire function, if you are taking a string like "12345" and just want to put a period after each number and at the end, then there are easier ways to do it than what you have:
text = text.replace(/(.)/g, '$1.');
Will do it.
input.value = num+'.';
or like this
var num = b.split('').reverse().join('').replace(/^[\.]/,'').replace(/$/, ".");
/$/ means end of the string
or like this
var num = b.split('').reverse().join('').replace(/^(.{1})(.+)/, '$2$1');
Take a look at this post:
Move n characters from front of string to the end
enjoy
I am new in programing and right now I am working on one program. Program need to find the substring in a string and return the index where the chain starts to be the same. I know that for that I can use "indexOf". Is not so easy. I want to find out substrings with at moste one different char.
I was thinking about regular expresion... but not really know how to use it because I need to use regular expresion for every element of the string. Here some code wich propably will clarify what I want to do:
var A= "abbab";
var B= "ba";
var tb=[];
console.log(A.indexOf(B));
for (var i=0;i<B.length; i++){
var D=B.replace(B[i],"[a-z]");
tb.push(A.indexOf(D));
}
console.log(tb);
I know that the substring B and string A are the lowercase letters. Will be nice to get any advice how to make it using regular expresions. Thx
Simple Input:
A B
1) abbab ba
2) hello world
3) banana nan
Expected Output:
1) 1 2
2) No Match!
3) 0 2
While probably theoretically possible, I think it would very complicated to try this kind of search while attempting to incorporate all possible search query options in one long complex regular expression. I think a better approach is to use JavaScript to dynamically create various simpler options and then search with each separately.
The following code sequentially replaces each character in the initial query string with a regular expression wild card (i.e. a period, '.') and then searches the target string with that. For example, if the initial query string is 'nan', it will search with '.an', 'n.n' and 'na.'. It will only add the position of the hit to the list of hits if that position has not already been hit on a previous search. i.e. It ensures that the list of hits contains only unique values, even if multiple query variations found a hit at the same location. (This could be implemented even better with ES6 sets, but I couldn't get the Stack Overflow code snippet tool to cooperate with me while trying to use a set, even with the Babel option checked.) Finally, it sorts the hits in ascending order.
Update: The search algorithm has been updated/corrected. Originally, some hits were missed because the exec search for any query variation would only iterate as per the JavaScript default, i.e. after finding a match, it would start the next search at the next character after the end of the previous match, e.g. it would find 'aa' in 'aaaa' at positions 0 and 2. Now it starts the next search at the next character after the start of the previous match, e.g. it now finds 'aa' in 'aaaa' at positions 0, 1 and 2.
const findAllowingOneMismatch = (target, query) => {
const numLetters = query.length;
const queryVariations = [];
for (let variationNum = 0; variationNum < numLetters; variationNum += 1) {
queryVariations.push(query.slice(0, variationNum) + "." + query.slice(variationNum + 1));
};
let hits = [];
queryVariations.forEach(queryVariation => {
const re = new RegExp(queryVariation, "g");
let myArray;
while ((searchResult = re.exec(target)) !== null) {
re.lastIndex = searchResult.index + 1;
const hit = searchResult.index;
// console.log('found a hit with ' + queryVariation + ' at position ' + hit);
if (hits.indexOf(hit) === -1) {
hits.push(searchResult.index);
}
}
});
hits = hits.sort((a,b)=>(a-b));
console.log('Found "' + query + '" in "' + target + '" at positions:', JSON.stringify(hits));
};
[
['abbab', 'ba'],
['hello', 'world'],
['banana', 'nan'],
['abcde abcxe abxxe xbcde', 'abcd'],
['--xx-xxx--x----x-x-xxx--x--x-x-xx-', '----']
].forEach(pair => {findAllowingOneMismatch(pair[0], pair[1])});
This is the script that i am using to fetch a particular cookie lastvisit :
AFTER THE EDIT
// This document writes a cookie
// called from index.php
window.onload = makeLastVisitCookie;
function makeLastVisitCookie() {
var now = new Date();
var last = new Date();
now.setFullYear(2020);
// set the cookie
document.cookie = "lastvisit=" + last.toDateString() + ";path=/;expires=" + now.toGMTString();
var allCookies = document.cookie.split(";");
for( var i=0 ; i < allCookies.length ; i++ ) {
if(allCookies[i].split("=")[0]== "lastvisit") {
document.getElementById("last_visit").innerHTML = "You visited this site on" + allCookies[i].split("=")[1];
} else {
alert("testing..testing..");
}
}
}
From this script the if part never works though there are 5 cookies stored from my website. (including the cookie that i am saving from this script) What is the mistake that i am making while fetching the cookie named lastvisit ?
You're splitting the cookie by ; an comparing those tokens with lastvisit. You need to split such a token by = first. allCookies[i] looks like key=val and will never equal lastvisit. Een if allCookies[i] == "lastvisit" is true, the result will still not be as expected since you're showing the value of allCookies[i + 1] which would be this=the_cookie_after_lastvisit.
if(allCookies[i].split("=") == "lastvisit") { should be:
var pair = allCookies[i].split("=", 2);
if (pair[0].replace(/^ +/, "") == "lastvisit") {
"You visited this site on" + allCookies[i+1]; should be:
"You visited this site on" + pair[1];
The 2 argument of split makes cookies like sum=1+1=2 be read correctly. When splitting cookies by ;, the key may contain a leading space which much be removed before comparing. (/^ +/ is a regular expression where ^ matches the beginning of a string and + one or more spaces.)
Alternatively, compare it directly against a RE for matching the optional spaces as well (* matches zero or more occurences of a space character, $ matches the end of a string):
if (/^ *lastvisit$/.test(pair[0])) {
I've tested several ways to get a cookie including using regular expressions and the below was the most correct one with best performance:
function getCookie(name) {
var cookie = "; " + document.cookie + ";";
var search = "; " + encodeURIComponent(name) + "=";
var value_start = cookie.indexOf(search);
if (value_start == -1) return "";
value_start += search.length;
var value_end = cookie.indexOf(';', value_start);
return decodeURIComponent(cookie.substring(value_start, value_end))
}
You need to remove possible white space around the cookie key before comparing to the string "lastvisit". This is done conveniently using regular expressions. /^\s+/ matches all white space at the beginning, /\s+$/ matches all white space at the end. The matches are replaced by the empty string, i.e. removed:
for( var i = 0 ; i < allCookies.length ; i++ ) {
var c = allCookies[i].split("="); // split only once
var key = c[0].replace(/^\s+/, '').replace (/\s+$/, ''); // remove blanks around key
if (key == "lastvisit") {
document.getElementById("last_visit").innerHTML = "You visited on " + c[1];
}
//...
}
The problem statement is like this: I have a contract. On renewal on every month the contract name should append with renewal identifier. For example at beginning the name is myContract then on first renewal name should be myContract-R1, next renewal name should be myContract-R2 and so on.. On each renewal, the name should automatically change. So in Jquery how can I do this?
This is a JavaScript question, not a jQuery question. jQuery adds little to JavaScript's built-in string manipulation.
It sounds like you want to take a string in the form "myContract" or "myContract-Rx" and have a function that appends "-R1" (if there's no "-Rx" already) or increments the number that's there.
There's no shortcut for that, you have to do it. Here's a sketch that works, I expect it could be optimized:
function incrementContract(name) {
var match = /^(.*)-R([0-9]+)$/.exec(name);
if (match) {
// Increment previous revision number
name = match[1] + "-R" + (parseInt(match[2], 10) + 1);
}
else {
// No previous revision number
name += "-R1";
}
return name;
}
Live copy
You can use a regular expression for this:
s = s.replace(/(-R\d+)?$/, function(m) {
return '-R' + (m.length === 0 ? 1 : parseInt(m.substr(2), 10) + 1);
});
The pattern (-R\d+)?$ will match the revision number (-R\d+) if there is one (?), and the end of the string ($).
The replacement will return -R1 if there was no revision number before, otherwise it will parse the revision number and increment it.
how you get renewal number? Calculating from date, or getting from database?
var renewal = 1,
name = 'myContract',
newname = name+'R'+renewal;
or maybe like
$(function(){
function renew(contract){
var num_re = /\d+/,
num = contract.match(num_re);
if (num==null) {
return contract+'-R1';
} else {
return contract.replace(num_re,++num[0]);
}
}
var str = 'myContract';
new_contract = renew(str); // myContract-1
new_contract = renew(new_contract); // myContract-2
new_contract = renew(new_contract); // myContract-3
});
Here jQuery can't help you. It's pure JavaScript working with strings
P.S. I have here simple reg exp, that's not concrete for your example (but it works). Better use reg-exp from example of T.J. Crowder