Develop Reference

This filter is not returning expected result

function get20(arr){
let result = arr.filter((theArtist) => {
let birth = Number(theArtist.years.splice(0,3))
let death = Number(theArtist.years.splice(7,10))
return birth >= 1900 && death <= 2000;
})
return result;
}
This keeps giving me the error "theArtist.years.splice is not a function" I do not understand why it isn't taking the first four and last four letters of the "years" string and turning them into numbers. the years string looks like "1971 - 1984"

You should use substring on strings (splice is a similar function for arrays). Also note your indexes were off by 1 !
var years = "1971 - 1984";
let birth = Number(years.substring(0,4))
let death = Number(years.substring(7,11))
console.log(birth,death)

Splice is a method for arrays, not strings. Try this:
years = theArtist.years.split('')
let birth = Number(years.splice(0,4))
let death = Number(years.splice(7,4))
Alternatively, use substring.
let birth = Number(theArtist.years.substring(0,4))
let death = Number(theArtist.years.substring(7,11))

Use slice instead splice:
'1971 - 1984'.slice(0,4) // '1971'
'1971 - 1984'.slice(7,11) // '1984'

easy way to multiply a value to successive substrings in javascript

Good morning, sorry for my poor English.
I'm a neophyte and I'm trying to create a javascript program that, given a string in input, if it finds inside defined substrings it returns a value to each substring and returns the sum of the values ​​found as output. Everything ok here. But I'm finding it difficult to manage the case where in front of the substring that I'm looking for, there's for example "2x" which means that the value of the next substring (or of all subsequent substring) is to be multiplied for 2. How can I write in simple code this exception?
Example:
A1 = 1
M1 = 1
input description = A1-M1
output = 2
input descritpion = 2 x A1-M1
output = 4
Thanks in advance

For more comprehesion, you can find my code below:
let str_description = "2 x A1-M1";
var time_mont = [];
var time_cloa = [];
if(str_description.includes("A1")){
time_mont.push (0.62);
} else {
time_mont.push (0);
}
if(str_description.includes("M1")){
time_mont.push (0.6);
} else {
time_mont.push (0);
}
How can I manage "2 x " subtring?

Add 0 before single digit number of time format [duplicate]

This question already has answers here:
Adding "0" if clock have one digit
(9 answers)
Closed 3 years ago.
How can we add 0 before single digit number of time format.
Like if I have a time "0:3:25" (hh:mm:ss) format to convert into "00:03:25"

You shouldn't overcomplicate this:
const time = "0:3:25";
const paddedTime = time.split(':').map(e => `0${e}`.slice(-2)).join(':')
console.log(paddedTime)
split the string by semicolons (:), that yields an array (hours, minutes, seconds). map this array with a function that adds a 0 before every item in the array, and slice the last two digits (you get an array again). Then join the resulting array by semicolons (and you get a string).
Or you could use a regex instead of the split:
const time = "0:3:25";
const paddedTime = time.match(/\d+/g).map(e => `0${e}`.slice(-2)).join(':')
console.log(paddedTime)
The last part is the same with regex (map, slice, join).
And you also could use the padStart() (JavaScript built-in function):
const time = "0:3:25";
const paddedTime = time.split(':').map(e => e.padStart(2, 0)).join(':')
console.log(paddedTime)
padStart() on MDN: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/padStart

You can do something like below (Explanations included):
const time = '0:3:25';
const correctedTime = parseTime(time);
console.log(correctedTime);
function parseTime(time){
return time
.split(':') // Split them into array as chunk of [hour, minute, second]
.map(pad) // Map them with `pad` function below
.join(':'); // Join them back into 'hh:mm:ss'
}
function pad(n){
return parseInt(n) < 10 // If number less than 10
? '0' + n // Add '0' in front
: n; // Else, return the original string.
}

you can add split the existing time string on the ":", then for each portion, add the "0" then take the last two characters. Then simply join the portions back into a striung.
let time = "0:3:25";
function updateTime(){
let newTimePortions = [];
let timePortions = time.split(":");
timePortions.forEach(function(portion,index) {
newTimePortions[index] = ("0" + portion).slice(-2)
})
return newTimePortions.join(':')
}
console.log(updateTime()); // gives 00:03:25

Please try below code
var dateinfo="0:3:25";
var newdate=dateinfo.split(":");
var hdate=newdate[0];
var mdate=newdate[1];
var sdate=newdate[2];
if(hdate.length == 1 ){
hdate="0"+hdate;
}
if(mdate.length == 1 ){
mdate="0"+mdate;
}
if(sdate.length == 1 ){
sdate="0"+sdate;
}
dateinfo=hdate+":"+mdate+":"+sdate;
This is work for me

Average calculator finding strange and incorrect numbers [duplicate]

This question already has answers here:
How to get numeric value from a prompt box? [duplicate]
(6 answers)
Closed 3 years ago.
I am trying to make an average calculator. This is my code for it:
var data = [];
var yesno = confirm("Would you like to add more data?");
while (yesno) {
var newdata = prompt("Enter a piece of data (must be a number)");
data.push(newdata);
var yesno = confirm("Would you like to add more data?");
}
var total = 0;
var i = 0;
if (!yesno) {
while (i < data.length) {
total += data[i];
i++;
}
}
var average = total / data.length;
document.write(average);
It seems to take input well, however something goes wrong when it comes to calculation. It says that the average of 6 and 6 is 33, 2 and 2 is 11, and 12 and 6 is 306. These are obviously wrong. Thank you in advance for your help.

You need to take a number, not a string value from the prompt.
The easiest was is to take an unary plus + for converting a number as string to a number
data.push(+newdata);
// ^
Your first example shows, with '6' plus '6', you get '66', instead of 12. The later divsion converts the value to a number, but you get a wrong result with it.

It is taking the input as string. Convert the input to floats before putting them in the array. I think its performing string additions like 6+6=66 and then 66/2 = 33. Similar is the case of 2 and 2.

javascript dynamic regex vs hard typed and captures

I've been at this for hours -- I think I need sleep... but no matter how I alter the expression javascript will only capture the 1st and 3rd elements:
var number = 09416;
var mat = "([0-9]+/[0-9]+/[0-9]+\\s+[0-9]+:[0-9]+)\\s+([A-Z]+)\\s+[0-9,]+\\s+(.*?"+number+".+)";
// month / day / year hour : min AMPM byte size filename containing number in middle
var pattern = new RegExp(mat,"gi");
var arr = ['09/07/2010 07:08 PM 1,465,536 BOL09416 BOL31.exe',
'09/06/2010 12:13 PM 110,225 BOL09416_BOL030.exe',
'09/08/2010 04:46 AM 60,564 BOL09416_BOL32.exe',
'09/08/2010 01:08 PM 63,004 bol09416_bol33.exe']
for (var i=0;i<arr.length;i++){
var match = pattern.exec(arr[i]);
alert(match);
}
It is all spaces (no tabs), I've rewriten the regex to be as explainatory as possible... It correctly matches on arr[0] and arr[2], but nulls on the other two.
Tried looking for possible typo's, trying different .+,.*,.+? etc. All online matchers show that it should be working: Example
Anybody have any ideas as to what I'm missing?
====================
Update:
Going through all the awesome suggestions I am stumped even further:
var match = arr[i].match(/([0-9]+\/[0-9]+\/[0-9]+\s+[0-9]+:[0-9]+)\s+([A-Z]+)\s+[0-9,]+\s+(.*?09416.+)/g);
gives match[0] = full string match[1] = undefined. Basically no captures.
where as:
var match = /([0-9]+\/[0-9]+\/[0-9]+\s+[0-9]+:[0-9]+)\s+([A-Z]+)\s+[0-9,]+\s+(.*?09416.+)/g.exec(arr[i]);
DOES return match[0] = full string, match[1] = date, and so on.
So I guess my real question is how to include dynamically made RegExpressions, and have multiple captures? As the only difference between:
var number = "09416";
var mat = "([0-9]+/[0-9]+/[0-9]+\\s+[0-9]+:[0-9]+)\\s+([A-Z]+)\\s+[0-9,]+\\s+(.*?09416.+)";
var pattern = new RegExp(mat,'g');
and
/([0-9]+\/[0-9]+\/[0-9]+\s+[0-9]+:[0-9]+)\s+([A-Z]+)\s+[0-9,]+\s+(.*?09416.+)/g.exec(arr[i]);
is that I hard-typed the number.

var number = 09416;
// month / day / year hour : min AMPM byte size filename containing number in middle
var mat = '^(\d{2}\/\d{2}\/\d{4})\s+(\d{2}:\d{2}\s*[AP]M)\s+((\d+[\d,]?))\s+(.' + number + '.*)$';
var pattern = new RegExp(mat);
var arr = ['09/07/2010 07:08 PM 1,465,536 BOL09416 BOL31.exe',
'09/06/2010 12:13 PM 110,225 BOL09416_BOL030.exe',
'09/08/2010 04:46 AM 60,564 BOL09416_BOL32.exe',
'09/08/2010 01:08 PM 63,004 bol09416_bol33.exe']
for (var i=0;i<arr.length;i++){
var match = arr[i].match(pattern);
console.log(match);
}
Use string.match instead of regex.exec.
Edited
I've removed the global and it worked like it should be. I've also rewritten the regex but it's quite close to yours (not a big deal).
Look at the output by firebug below:
["09/08/2010 04:46 AM ...,564 BOL09416_BOL32.exe", "09/08/2010", "04:46 AM", "60,564", "564", "BOL09416_BOL32.exe"]
0 "09/08/2010 04:46 AM ...,564 BOL09416_BOL32.exe" //whole match
1 "09/08/2010" //date
2 "04:46 AM" //time
3 "60,564" //bytes
4 "564" // last digit of bytes (i can't take this off. but it's harmless)
5 "BOL09416_BOL32.exe" //name of file

I would suggest you try Regexr to build the expression.
try this
([0-9]+/[0-9]+/[0-9]+ +?[0-9]+:[0-9]+) +?([A-Z]+) +?[0-9,]+ +?(.*?09416.*)

Try this regex:
new RegExp('([0-9]+/[0-9]+/[0-9]+\\s+[0-9]+:[0-9]+)\\s+(AM|PM)\\s+([0-9,]+)\\s+([^0-9]*'+number+'.+)','gi')
Time
AM/PM
File size
File name