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In this function, am expecting the return value to be increment of variable value . However , i am getting original value ,
here is my function:
var num = function(){
var a = 0;
return a++;
}
alert(num()); //it giving the result as 0 instead of 1...why?
can anyone please explain this to me?
The ++ acts after the 'return':
return a++ ==> return a, then add 1 to a
return ++a ==> add 1 to a, then return
Look at this answer.
try
var num = function(){
var a = 0;
return ++a;
}
++a give the value after operation a++ give the value then do the operation
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I'm not so good with regex or trying to return the side part of a string. Can someone help me figure this out. I have a demo below.
str = "<html><head><script>var x = '123';</script></head></html>";
console.log(str)
// should return var x = '123';
Someone wrote a very good regex for stripping tags:
var strippedStr = str.replace(/(<([^>]+)>)/ig,"");
console.log(strippedStr);
Source: http://css-tricks.com/snippets/javascript/strip-html-tags-in-javascript/
I played around a bit with it and found a way with match using groups:
str.match(/(>)([^><]+)(<\/)/m)[2]
result = "var x = '123';"
=> a range (2nd group) beginning by ">" (1st group) and ending with "var x = '123';
I am not sure it'll cover all the cases...
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In PHP, we can assign a variable AND test it at the same time:
<?php
if ($result = $this->find()) {
$this->do_something($result);
}
function find() {
if ($this->day == 'Sunday')
return '1234';
else
return false;
}
In the above example, on Sundays, $result is set to '1234' and calls the do_something function. On other days, it is set to false and nothing else occurs.
Is this kind of thing possible with Javascript?
Yes, it is possible.
var day=[
'Sunday','Monday','Tuesday','Wednesday','Thursday','Friday','Saturday',
][new Date().getDay()];
if(result = find()){
do_something(result);
}
function find(){
if(day == 'Sunday')
return '1234';
else
return false;
}
Tada! Calls do_something on Sundays.
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Can anyone explain what is meaning of this Regular Expression?
/^(https?):\/\/(www\.)?[a-zA-Z0-9\-\.]+\.[a-zA-Z0-9]{2,3}[a-zA-Z0-9\-\#\.\/\?]*$/
Finally I have founded my solution:
function validateURL(url)
{
var re = /^(https?):\/\/(www\.)?[a-z0-9\-\.]+\.[[a-z0-9\-\.\/]{2,}]*$/;
if (!re.test(url))
{
return false;
}
else
{
return true;
}
}
this function return true if your url contain these:
part 1. https or http
part 2. www or not (means optional).
Below image exploring in more depth.
I am wrong?
I've tried the following and works fine for me.
var url = "https://www.xyz.xe";
function validateURL(url)
{
var urlregex = new RegExp("^(http|https)\://([a-zA-Z0-9\.\-]+(\:[a-zA-Z0-9\.&%\$\-]+)*#)*((25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9])\.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9]|0)\.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9]|0)\.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[0-9])|([a-zA-Z0-9\-]+\.)*[a-zA-Z0-9\-]+\.(com|edu|gov|int|mil|net|org|biz|arpa|info|name|pro|aero|coop|museum|[a-zA-Z]{2}))(\:[0-9]+)*(/($|[a-zA-Z0-9\.\,\?\'\\\+&%\$#\=~_\-]+))*$");
return urlregex.test(url);
}
validateURL(url);
Returs false when url="https://www.xyz.x" and true when url="https://www.xyz.xe"
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Say I have a range which consists of < -10 and I split this up using a regex call which leaves me with < -10.
I then have a function which gets me the number from the split and I call it like range1.getMin(), this would return -10 but when I use range1.getMin().indexOf('-') it doesn't work.
Try comparing to zero:
var isNegative = range1.getMin() < 0;
function isMin(value) {
if(value<0) {
return true;
}
return false;
}
You could add a check like eval() for the value to make sure you're dealing with an integer.
Also, if you need to make sure you have a positive number (or negative number for that matter) before you use the number in your process, you can Math.abs() your number to make sure it's always a positive number.
var val = parseInt("-10", 10)
can be used to parse integer and to test for positive number
val >= 0
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I don't know where to start with this. Am I missing some knowledge I would need to know? Any hints you could give me or a solution I could dissect?
A geometric sequence is ar0, ar1, ar2, ... yes?
function isGeometric(arr) {
if (arr.length <= 2) return true; // special cases
var a = arr[1], // we dont need to test before this
r = a / arr[0], // ratio of first 2
i;
for (i = 2; i < arr.length; ++i)
if ((a *= r) !== arr[i])
return false;
return true;
}
isGeometric([2, 4, 8]); // true
isGeometric([2, 4, 5]); // false