Getting a substring from a string using regex

Question

I am trying to search for a substring on a given string.

// format is <stringIndex>~<value>|<stringIndex>~<value>|<stringIndex>~<value>
var test = "1~abc1|2~def2|1~ghi3|4~jk-l4|5~123|6~sj2j";

function getValue(test, stringIndex) {
    // format is <stringIndex>~<value>|<stringIndex>~<value>|<stringIndex>~<value>
    //help with this.
    //I can only get the value if 1 is the passed parameter, here is the code:
    return test.replace(new Regexp(stringIndex + '\~(.+?(?=\|)).+'), '$1');
}

// usage:

getValue(test, '1'); //returns 'abc1', even though there are two 1's
getValue(test, '4'); //returns 'jk-14'
getValue(test, '6'); //returns 'sj2j'
getValue(test, '123213'); // returns ''

Basically, I'm writing a function which accepts the test string and stringIndex as a parameter, and searches the test string using that stringIndex and return the value associated with it. the format of the test string is stated above in the comments. I'm only looking for regex solution without using loops or split.

Please spell out more clearly what your desired output is. Use the g flag on your regex to do a global replace. — nnnnnn
– nnnnnn, Commented Dec 4, 2014 at 5:53

anubhava · Accepted Answer · 2014-12-04 06:10:23Z

1

You probably want this regex code:

function getValue(test, stringIndex) {
    // format is <stringIndex>~<value>|<stringIndex>~<value>|<stringIndex>~<value>
    //help with this.
    //I can only get the value if 1 is the passed parameter, here is the code:
    var m = test.match(new RegExp(stringIndex + "~([^|]+)", 'i')) || [null, null];
    return m[1];
}

Then calling it as:

getValue(test, '1');
"abc1"
getValue(test, '4');
"jk-l4"
getValue(test, '6');
"sj2j"
getValue(test, '123213');
null

edited Dec 4, 2014 at 6:10

answered Dec 4, 2014 at 5:59

anubhava

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Comments

user3728205 · Accepted Answer · 2014-12-04 07:38:47Z

Here is an update for the above two answers, we need to add "\b" for the regexp.

// modified the test string.
var test = "311~abc1|2~def2|1~ghi3|4~jk-l4|5~123|6~sj2j";
function getValue(test, stringIndex) {
    var m = test.match(new RegExp("\\b" + stringIndex + "~([^|]+)", 'i')) || [null, null];
    return m[1];
}

> getValue(test, '1');
'ghi3'
> getValue(test, '2');
'def2'
> getValue(test, '11');
null
> getValue(test, '311');
'abc1'

Leo · Accepted Answer · 2014-12-04 06:16:34Z

0

There are plenty ways of writing regular expression for matching a pattern, it really depends on the specificity of your use case. Here is one solution:

var test = "1~abc1|2~def2|1~ghi3|4~jk-l4|5~123|6~sj2j";
function getValue(test, stringIndex) {
    var matches = test.match(new RegExp(stringIndex + "~([\\w-]+)\\|?"));
    return matches ? matches[1] : "";
}

getValue(test, '1'); // 'abc1'
getValue(test, '4'); // 'jk-14'
getValue(test, '6'); // 'sj2j'
getValue(test, '123213'); // ''

edited Dec 4, 2014 at 6:16

answered Dec 4, 2014 at 6:03

Leo

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