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The documentation specifies that the first arg in parseInt is the number you want mutated and the second arg is the base you want to convert it to. But when I try to use it as such it returns NaN instead of an integer. Why is this?
parseInt(65, 60)
>>>NaN
From http://www.ecma-international.org/ecma-262/5.1/#sec-15.1.2.2
Step 8a:
If R < 2 or R > 36, then return NaN.
That's why.
It's just a arbitrary rule to simplify implementation, probably.
Edit: see comment for the probable reason.
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Hi i was reading a article and found pretty strange results the below code in javascript return 2.
!+[]+!+[]
Can anyone please explain.
Breaking down the expression into the correct order of operations, you have:
(!(+[])) + (!(+[]))
First things first, [] is cast to a number by +, which results in 0. Don't ask me why, it just does :p Probably buried in the specification somewhere.
!0 is simply true
So you end up with true + true, which again casts to numbers, resulting in 1 + 1 = 2
To get nine, you'd need nine repetitions:
!+[]+!+[]+!+[]+!+[]+!+[]+!+[]+!+[]+!+[]+!+[] == 9
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I am just curious how you can get the total number of vowels in a string. I know this is a very simple function, but I am new to Javascript. Thanks for the help
You can remove all characters that are not vowels and count the remaining ones:
var str = /* something*/,
numberVowels = str.replace(/[^aeiou]/ig, '').length;
Where
/[^aeiou]/ matches single character NOT present in the list "aeiou"
i is the case-insensitive flag, to count AEIOU too.
g is the global flag, to replace ALL characters which are not vowels, instead of just the first one.
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I have getting string. I want to check string have any digit.
The string may be -
var val="1"; or val=",,"; or val = "1,2,0";
I want to check if val have any digit.
function hasDigit(yourString) {
return yourString.match(/\d/) !== null;
}
Here's a fiddle demo: http://jsfiddle.net/VpLgG/
You can use yourInputString.match(/[0-9]/g), or what Jonah has specified. This will return null if there are not digits else it will return the values present inside the string that will match separated by comma.
Javascript side :
if (/\d/.test(val)) {
// do something
}
Not really useful but required to get attention apparently (demo here)...
function hasDigit(val) {
return /\d/.test(val);
}
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp/test
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I have a phone number like (123) 456-7891. I need number like 1234567891.
How can I do that in Javascript ?
To be on the safe side, I would recommend removing everything except + (for country codes) and digits:
result = subject.replace(/[^+\d]+/g, "");
You can use String.replace() to do this. Pass it a RegExp that matches everything but digits and replace them with ''.
var number = '(123) 456-7891';
number = number.replace(/[^\d]/g, '');
alert("(123) 456-7891".replace(/[\(\)\-\s]+/g, ''));
please check this link.it might help you
http://www.w3resource.com/javascript/form/phone-no-validation.php
there are many examples here.it might be useful for you.
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Can someone tell me how to replace the number "2" with another number in this string"? For example, if it's a 2, it should be a 3, if it's a 3 it should be a 4, etc.
Please note that the number can be any number from 1 through 5.
/img/tmp/2_th.jpg
Just use String#replace:
s.replace(/\d+(?=_)/, "replaced");
To replace any number from 1-5 use:
s.replace(/[1-5](?=_)/, "replaced");
Here (?=_) is used a positive lookahead which makes sure match a number which is followed by underscore _.
UPDATE: Based on your edit you can use this code to increment matched number by 1:
s.replace(/([1-5])(?=_)/, function(n) {return parseInt(n)+1;});
Read More About Lookarounds in Regex
I understand from your question that you want to replace any number by the following one (" if it's a 2, it should be a 3, if it's a 3 it should be a 4").
Then you can do this :
var input = "/img/tmp/2_th.jpg";
var output = input.replace(/\d+/g,function(s){ return +s+1 })
Result :
"/img/tmp/3_th.jpg"