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I have to extract a string from backwards upto 10 digits.
Use case is when we select a mobile number it is prefixed with country code sometimes and sometimes we get only the mobile number.
Let's say the number is : +91-84040355236545
I have to extract the number from the end say from 5 to last 10 degits so the end result would be 0355236545
I have a solution of using string.substring method
Here's a simple solution using substrings:
var number = "+91-84040355236545";
var lastTenDigitsNumber = number.substr(number.length - 10);
console.log(lastTenDigitsNumber);
A simpler solution is using slice:
var number = "+91-84040355236545";
console.log(number.slice(-10));
Another solution using a function and RegEX:
function extractTenDigits(number) {
var rx = /(\d{10}$)/g;
var arr = rx.exec(number);
return arr[1];
}
var number = "+91-84040355236545";
console.log(extractTenDigits(number));
I did a simple benchmark and the best solution for small quantity of numbers is the one using slice.
If you provide more details I can provide a more tailored suggestion.
You can try the following using substring :
let str = "+91-84040355236545";
str.substr(str.length - 10 ,10);
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I have other ways of doing the same thing .. So I am not looking for a different solution to this problem ... I am looking for an explanation as to why if I have defined a integer, it still concatenates with .map as if it were a string.
I have a basic set of data retrieved from an API:
"data":["8","8","12","1","7","4","2"]
If I map it using
let count = response.data.metrics.data.map((item) => + parseInt(item));
I am having a hard time understanding why it's treating this as a string returning
88121743
When I feel like because I am parsing it as an integer it should add and come out with 42.
Is this just an issue just using .map? Can shortcut math functions be used here?
Here is my Reproducible Example
Your current approach using Array#map creates a new array with each element converted to a number. React renders this array as multiple text nodes, so it looks like a single string.
To sum the values, use Array#reduce with parseFloat/parseInt, the Number function, or the unary plus operator to convert each string to a number.
const visitCount = data.reduce((a,b) => a + parseFloat(b), 0);
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I have this line.
let x = "Categories=All&Search=hat&ListPage=15&Page=1";
How to use regular expressions to say what you need to take from the beginning of a line and up to 2 characters &.Categories=All&Search=hat&
Use split and pass the limit argument, then just reconstruct it back into a string (if you really need the & - if not, discard everything after the split):
let x = "Categories=All&Search=hat&ListPage=15&Page=1";
const res = x.split("&", 2).map(e => e + "&").join("");
console.log(res);
You can use /([^&]*&){2}/g regex to match what you want.
let x = "Categories=All&Search=hat&ListPage=15&Page=1";
let y = x.match(/([^&]*&){2}/g);
console.log(y);
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If I have phone number ranges such as 5555555555-5599 5555550000-0003 5555550005-0007, my mission is to have it return all results without using a server. Is it possible for it to return without a server a result that would look like:
5555555555
5555555556
5555555557
/* etc */
My previous post about javascript has helped me up to this point but I wanted to rehaul the whole site.
Javascript dashes in phone number
If you could point me in the right direction, I would really appreciate it. I'm just having a mind block right now if this is even possible.
Given a single phone range in the form of "xxxxxxyyyy-zzzz", split the whole string on the dash and the first part of the string at the 6th index. This yields three strings "xxxxxx", "yyyy", and "zzzz". Using a for loop, you can create an array of phone numbers by concatenating the prefix "xxxxxx" onto the range "yyyy"-"zzzz":
// Get an array from a given range "xxxxxxyyyy-zzzz"
function fromRange(range) {
var phoneNumArray = [];
var prefix = range.substring(0,5);
var suffixRange = range.split("-");
for (var suffix = suffixRange[0].substring(4, -1);suffix < suffixRange[1];suffix++) {
phoneNumArray.push(prefix + suffix);
}
return phoneNumArray;
}
Try it in JSFiddle.
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How to use a while loop to generate random numbers until a certain number is reached? Help please
This code will generate integer numbers from 1 until 50.
var number = 50;
var x = 0;
while(x !== number){
x = Math.floor((Math.random() * 50) + 1);
console.log(x);
}
Considering there is a random number generator random you will just do as shown below
do
{
x=Math.random();
x=x*range;
if(x is desired number )
break;
else
{
print the number.
}
}while(1)
print -( desired number found).
NOTE: As you are beginner you can try the following when designing these codes..
First find what is the input and what is the output.
Then try to draw a flow chart of the whole thing ( You can try running it yourself as if you are the computer)
Then all the branch and loop are converted to if-else or for-while loop.
Check the code and match input and output.
This is a basic program structure..Instead of asking in forums about common structures try reading some books.
Hint 1: There is a function in javascript called Math.random() return a random number between 0 (inclusive) and 1 (exclusive):
Hint 2: check whether the values are equal. Use === in javascript.
Hint 3: check for if else, break and do while, while loop.
Hint 4: If you are given a random number 0<=x<1 then how do you generate a random number using in range [a,b) using the abobe geerated number? Ans: Use b*x.
hope this helps.
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I need to generate a random letter from A-Z multiple times on my page when it refresh or reload. may be i am a bit confused here whether i can create a array for storing all alphabets and use .random method of javascript . i'm pretty sure we need to use random here. But there is any other simple way for doing this in jquery.
I don't think there's a simpler way of doing this with jQuery. You'll have to use the random method to generate the desired text. Try something like:
function generateRandomText(n) {
var text = '';
for (var i = 0; i < n; i++) {
text += String.fromCharCode(65 + Math.floor(Math.random() * 26) + 32 * (Math.round(Math.random())));
}
return text;
}
The Math.floor(Math.random() * 26) bit picks a letter, and Math.round(Math.random()) gives a random 0 or 1 value, that decides the case(upper and lower respectively)
DEMO
use random with String.fromCharCode as,
String.fromCharCode(Math.floor(Math.random()*26+65))
This will give you a random alphabet each time.