extracting values from string in JavaScript

Question

Given a string of the form "(a,{b:c,d:e,f:g},h})", I want to extract a,c,e,g,h from the string. i.e. string will always contain 3 parameters, where 2nd parameter is of the form {b:c,d:e,f:g} i.e. it contains key value pairs and there can be any number of them. I want to extract all the values leaving behind keys.

Also I want to extract first and third parameter i.e. a and h in the above string. I am trying to scan the string and extract on character by character bases but I am not able to do extract values from 2nd argument.

Is there any efficient method to do it may be using regular expressions ?

why have that string? is it intentionally malformed? can you do something about the formatting? — Joseph
– Joseph, Commented May 26, 2012 at 8:02
@JosephtheDreamer yes it is intentionally stored as above format. — niting112
– niting112, Commented May 26, 2012 at 8:03

Blender · Accepted Answer · 2012-05-26 08:00:28Z

1

Try this regex:

\(([a-zA-Z0-9_\-]+),\{([a-zA-Z0-9_\-]+):([a-zA-Z0-9_\-]+),([a-zA-Z0-9_\-]+):([a-zA-Z0-9_\-]+),([a-zA-Z0-9_\-]+):([a-zA-Z0-9_\-]+)\},([a-zA-Z0-9_\-]+)\}\)

The first group is a, second is b, etc:

> str.match(/\(([a-zA-Z0-9_\-]+),\{([a-zA-Z0-9_\-]+):([a-zA-Z0-9_\-]+),([a-zA-Z0-9_\-]+):([a-zA-Z0-9_\-]+),([a-zA-Z0-9_\-]+):([a-zA-Z0-9_\-]+)\},([a-zA-Z0-9_\-]+)\}\)/)
["(a,{b:c,d:e,f:g},h})", "a", "b", "c", "d", "e", "f", "g", "h"]

answered May 26, 2012 at 8:00

Blender

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1 Comment

niting112 Over a year ago

Sorry for not making the question much clearer. a,b,c,d,e,f,g,h all are some strings in themselves.

Jeremy Goodell · Accepted Answer · 2012-05-26 08:15:21Z

0

Here's a complicated solution using the versatile split function:

var str = "(a,{b:c,d:e,f:g},h)"
var outstr = "";

var parts = str.split(",");
for (var ixPart = 0; ixPart < parts.length; ++ixPart) {
    if (ixPart > 0) outstr += ",";
    var part = parts[ixPart];
    if (part.indexOf(":") > 0) {
        var parts2 = parts[ixPart].split(":");
        var part2 = parts2[1];
        if (part2.indexOf("}") >= 0)
           outstr += part2.substring(0, part2.indexOf("}"));
        else outstr += part2;
    } else {
       if (part.indexOf("(") == 0) outstr += part.substring(1);
       else if (part.indexOf(")") >= 0)
           outstr += part.substring(0, part.indexOf(")"));
       else outstr += part;
    }
}

return outstr;

answered May 26, 2012 at 8:15

Jeremy Goodell

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2 Comments

Jeremy Goodell Over a year ago

BTW, I am assuming that the final } just before the final ) is a typo. That is, the } after the "h". If it isn't a typo, then my code needs further modification ...

Jeremy Goodell Over a year ago

I am pretty sure it will NOT work faster than regex processing. But it was kind of fun to write it.

Mark M · Accepted Answer · 2012-05-26 08:41:53Z

0

How about:

var testString = "(a,{b:c,d:e,f:g},h)";

var parameterArray = testString.split(/\((.+?),\{.+?:(.+?),.+?:(.+?),.+?:(.+?)\},(.+?)\)/);

This assumes that the }) at the end of the sample string is a type-o, but it's easy to modify if not.

edited May 26, 2012 at 8:41

answered May 26, 2012 at 8:30

Mark M

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Comments

HBP · Accepted Answer · 2012-05-26 09:14:45Z

0

Divide and conquer!

function extract (str) {
  str = str.trim ().split (/\s*,\s*/); // split on , chars with optional surrounding spaces
  return str.map (function (v) { // create array from values
    // remove prefix and/or suffix from required values :
    // first ignore any leading ( or { chars
    // then ignore a single word followed by :
    // use the following trimmed string as the data
    // ignore any ) or } at the end  
    return (v.match (/^[({]*(?:\w\s*:\s*)?\s*(.*?)\s*[)}]*$/) || ['', v]) [1];
  });
}

This assumes that the data strings will never :

be blank
contain , characters
begin with ( or {
end with ) or }

answered May 26, 2012 at 9:14

HBP

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Comments

Kayo · Accepted Answer · 2012-05-26 12:33:30Z

If the format of the string is known as you described, I would first edit the string to make it into JSON and then use eval

Example:

var str1 = "('word1',{b:'word2',d:'word3',f:'word4'},'word5')";

// Edit the string to JSON format by replacing '(' and ')' with '[' and ']'
var str2 = str1.replace(/\(/, '[').replace(/\)/, ']')

// str2 is now => "['word1',{b:'word2',d:'word3',f:'word4'},'word5']"

var obj = eval(str2);

// All you results are now in obj.

var result1 = obj[0]; // This gets'word1'

//Similarly you can get the rest as follows:
obj[1].b // This gives you 'word2'
obj[1].d // 'word3'
obj[1].f // 'word4'
obj[2]   // 'word5'

If obj[1] has a variable number of key/value pairs and you want only value you can iterate over the object obj[1] as follows:

for (var key in obj[1]) {
  obj[1][key];  // This gives the values in each iteration
}

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