JavaScript - How to get at specific value in a string?

Question

I have a string from which I am trying to get a specif value. The value is buried in the middle of the string. For example, the string looks like this:

 Content1Save

The value I want to extract is "1";

Currently, I use the built-in substring function to get to remove the left part of the string, like this:

MyString = "Content1Save";
Position = MyString;
Position = Position.substring(7);
alert(Position); // alerts "1Save"

I need to get rid of the "Save" part and be left with the 1;

How do I do that?

+++++++++++++++++++++++++++++++++++++++++ ANSWER

Position = Position.substr(7, 1);

QUESTION

What's the difference between these two?

Position = Position.substr(7, 1);
Position = Position.substring(7, 1);

Do you KNOW that you will be saving a NUMBER from the middle of a string with nothing but LETTERS around it? — josh.trow
– josh.trow, Commented Aug 16, 2011 at 17:08
Regarding your update, have a look at developer.mozilla.org/en/JavaScript/Reference/Global_Objects/… and developer.mozilla.org/en/JavaScript/Reference/Global_Objects/… — Felix Kling
– Felix Kling, Commented Aug 16, 2011 at 17:35

FishBasketGordo · Accepted Answer · 2011-08-16 17:27:51Z

4

You can use the substr^[MDN] method. The following example gets the 1 character long substring starting at index 7.

Position = Position.substr(7, 1);

Or, you can use a regex.

Position = /\d+/.exec(Position)[0];

edited Aug 16, 2011 at 17:27

answered Aug 16, 2011 at 17:08

FishBasketGordo

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Comments

dennmat · Accepted Answer · 2011-08-16 17:10:16Z

3

I would suggest looking into regex, and groups.

Regex is built essentially exactly for this purpose and is built in to javascript. Regex for something like Content1Save would look like this:

rg = /^[A-Za-z]*([0-9]+)[A-Za-z]*$/

Then you can extract the group using:

match = rg.exec('Content1Save');
alert(match[1]);

More on regex can be found here: http://en.wikipedia.org/wiki/Regular_expression

answered Aug 16, 2011 at 17:10

dennmat

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Comments

Alex Turpin · Accepted Answer · 2011-08-16 17:08:13Z

1

It highly depends on the rules you have for that middle part. If it's just a character, you can use Position = Position.substring(0, 1). If you're trying to get the number, as long as you have removed the letters before it, you can use parseInt.

alert(parseInt("123abc")); //123
alert(parseInt("foo123bar")); //NaN

answered Aug 16, 2011 at 17:08

Alex Turpin

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Comments

cwallenpoole · Accepted Answer · 2011-08-16 17:10:30Z

1

If you're actually trying to search, you'll more often than not need to use something called Regular Expressions. They're the best search syntax JavaScript avails.

var matches = Position.match(/\d+/)
alert(matches[0])

Otherwise you can use a series of substr's, but that implies you know what is in the string to begin with:

MyString.substr(MyString.indexOf(1), 1);

But that is a tad annoying.

answered Aug 16, 2011 at 17:10

cwallenpoole

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