how to extract ip address from string variable in javascript

Question

i have written bellow code in javascript

function reg()
{
    var a="ec2-54-234-174-228.compute-1.amazonaws.com";
    var r = a.match(/\-[0-9]*/g);
    alert(r);
}

i got output like -54,-234,-174,-228,-1 but i need to extract only 54-234-174-228 IP address from variable a.

The hostname-extraction does not work if the hostname naming strategy is changed at some later time by amazon and if it then does not anymore include the IP address's numbers. E.g. it could be hello-xaby.compute-1.amazonaws.com in the future. Do not try to extract the IP with string operations from the hostname. Instead, do a DNS lookup. — Daniel S.
– Daniel S., Commented Sep 3, 2013 at 9:38
my output is wrong because it also include -1 that is unnecessary for me. please can anyone write code for that? — Jaydipsinh
– Jaydipsinh, Commented Sep 3, 2013 at 9:40

Amin Abu-Taleb · Accepted Answer · 2013-09-03 09:39:17Z

2

Try this:

function reg()
{
    var a="ec2-54-234-174-228.compute-1.amazonaws.com";
    var r = a.match(/\-[0-9-]*/g);
    alert(r[0].substring(1,r[0].length));
}

a.match(/\-[0-9-]*/g); will return [-54-234-174-228,-1]. Getting the first element and removing - from the beginning you get what your IP. You can also add this:

alert(r[0].substring(1,r[0].length).replace(/-/g, '.'));

to return it in IP shape: 54.234.174.228

answered Sep 3, 2013 at 9:39

Amin Abu-Taleb

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1 Comment

user Over a year ago

Don't forget IP addresses are reversed in reverse-records. In this case the IP associated with the reverse-record would be 228.174.234.54

Tibos · Accepted Answer · 2013-09-03 09:39:32Z

2

Try this regexp: /[0-9]{1,3}(-[0-9]{1,3}){3}(?=\.)/

It matches a series of 4 numbers between 1 and 3 digits separated by -, which must be followed by a dot.

answered Sep 3, 2013 at 9:39

Tibos

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Comments

kangoroo · Accepted Answer · 2013-09-03 09:40:08Z

1

get the index of first "." then slice

function reg()
{
    var a="ec2-54-234-174-228.compute-1.amazonaws.com";
    var r = a.indexOf(".");
    alert(a.slice(0,r));
}

answered Sep 3, 2013 at 9:40

kangoroo

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1 Comment

iChux Over a year ago

Within the alert, change it to Array.prototype.slice.call(a.slice(0,r).split('-'), 1).join('-')

sabithpocker · Accepted Answer · 2013-09-03 09:45:20Z

1

"ec2-54-234-174-228.compute-1.amazonaws.com".split('.')[0].split('-').slice(1,5).join('.')

answered Sep 3, 2013 at 9:45

sabithpocker

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Comments

virtualmarc · Accepted Answer · 2013-09-03 09:42:46Z

0

In your case you can simply use this pattern:

var r = a.match(/([^a-z][0-9]+\-[0-9]+\-[0-9]+\-[0-9]+)/g);

answered Sep 3, 2013 at 9:42

virtualmarc

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Comments

Anton · Accepted Answer · 2013-09-03 10:05:27Z

0

One more example:

function reg() {
    var a="ec2-54-234-174-228.compute-1.amazonaws.com";
    var re = /-(\d+)/ig
    var arr = [];
    while(digit = re.exec(a)) arr.push(digit[1]);
    arr = arr.slice(0,4);

    alert(arr)
}

edited Sep 3, 2013 at 10:05

answered Sep 3, 2013 at 9:59

Anton

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Comments

Bhushan Kawadkar · Accepted Answer · 2013-09-03 10:08:05Z

0

you can use this regEx

"(\\d{2}-\\d{3}-\\d{3}-\\d{3})+"

edited Sep 3, 2013 at 10:08

answered Sep 3, 2013 at 9:46

Bhushan Kawadkar

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