basic javascript - taking the integer value out of a string

Question

Well, though I searched for learning sources I could not find the exact thing I wanted. Please help to improve this post rather than down-voting so that all new learners can improve their knowledge.

lets assume there is a variable

var y = "number12";

var z ="";

how to make z=12 (how take only the integer value out of y string variable)
how to make z=number13 (adding one to "number"+12 )

Have a look for "regular expressions". Alternatively you could try to split a string of this pattern into the non-number part and the number part (starting at the end of the string, checking if this character is still 0-9, going backwards, repeat). Increment the number part and combine those two parts back to a string again. — matthias, Sep 17 '14 at 14:05
Does the string always end in a number? Is the `number` text constant? — Alex K., Sep 17 '14 at 14:10

score 1 · Answer 1 · answered Sep 17 '14 at 14:10

1

You may try this,

var y = "number12";
x = parseInt(y.match(/[\d\.]*/));

answered Sep 17 '14 at 14:10

Tony Yip

705
5
14

score 1 · Accepted Answer · answered Sep 17 '14 at 14:15

1

Extract the number with a RegEx and then use parseInt to convert the string "12" to the number 12.

var y = "number12";
var x = parseInt( y.match(/\d+/) );
alert(x)

answered Sep 17 '14 at 14:15

mb21

34,845
8
116
142

what is the difference between x = parseInt(y.match(/[\d\.]*/)); and var x = parseInt( y.match(/\d+/) ); – nimala9 Sep 17 '14 at 14:23
1

The `\d` matches a single digit like `1` and `\d+` matches one or more digits like `12`. `\d*` would match zero or one digits.`[\d\.]*` doesn't appear to work. For mor info about regexes: http://www.regular-expressions.info/tutorial.html – mb21 Sep 17 '14 at 14:26

score 1 · Answer 3 · answered Sep 17 '14 at 14:24

1

Given that: @Alex K. yes number is a constant

Simply:

var x = "number" + (+y.substr(6) + 1);

answered Sep 17 '14 at 14:24

Alex K.

171,639
30
264
288

@ Alex K. can you expain what is the difference between x = parseInt(y.match(/[\d\.]*/)); and var x = parseInt( y.match(/\d+/) ); – nimala9 Sep 17 '14 at 14:26

score 0 · Answer 4 · edited May 23 '17 at 12:29

I agree with matthias

var input = "number12";

// define a regular expression to match your pattern
var re = /(\D+)(\d+)/;

// execute the regexp to get an array of matches
var parsed = re.exec(input);  // ['number12', 'number', '12']

// parse an integer value of the number
parsed[2] = parseInt(parsed[2], 10); // '12' ==> 12

// increment the number
parsed[2] += 1; // 12 ==> 13

// rejoin the string
input = parsed[1] + parsed[2]; // 'number' + 13 ==> 'number13'

basic javascript - taking the integer value out of a string

4 Answers4