JavaScript - How to get at specific value in a string?
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
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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);
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];
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
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
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.
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