Convert string in array form to actual array

Question

I have a text file in this format:

[[Line1TextA,[Lat,Long]], [Line1TextB,[Lat,Long]], ...]
[[Line2TextC,[Lat,Long]], [Line2TextD,[Lat,Long]], ...]
.
.
.

I am parsing a text file (done) and I want to convert strings in array format into actual array and store them as a variable to use.

I tried to use JSON.parse, as suggested here: Convert string containing arrays to actual arrays but I couldn't get it to work (syntax errors). Here is my attempt: https://jsfiddle.net/5yz95ktg/

var myStr = '[[Line1TextA,[Lat,Long]], [Line1TextB,[Lat,Long]]]'

var myArr = JSON.parse(myStr);
var myArr = JSON.parse("[" + myStr + "]");

Edit:

function readFile(query) {
    $.get('file.txt', function(data) {
        var lines = data.split("\n");    
        for (var i = 0, len = lines.length; i < len; i++) {
            if (lines[i].indexOf(query) > -1) { // Found a match
                var myArr = JSON.parse(lines[i]); // #NOT WORKING
            }
        }
    });
}

What is the error you are getting when using JSON.parse. Add actual sample array. — Tushar
– Tushar, Commented Oct 3, 2015 at 17:37
Console shows "Uncaught SyntaxError: Unexpected token". It is provided inside jsfiddle, but I will add it to the OP too. — Mohammad Ali
– Mohammad Ali, Commented Oct 3, 2015 at 17:38
Are the array values wrapped in quotes. If you directly put the array from file does it run? — Tushar
– Tushar, Commented Oct 3, 2015 at 17:41
You need to wrap the array values with quotes. jsfiddle.net/5yz95ktg/3 — NewToJS
– NewToJS, Commented Oct 3, 2015 at 17:42
provide demo with full example including csv parsing. Too many unknowns considering that the current demo works fine — charlietfl
– charlietfl, Commented Oct 3, 2015 at 17:45

Praveen Kumar Purushothaman · Accepted Answer · 2015-10-03 17:46:17Z

1

Well, you need to make sure they are strings:

var myStr = '[[Line1TextA,[Lat,Long]], [Line1TextB,[Lat,Long]]]'
//-------------^

So change it to:

var str = '[["Line1TextA",["Lat","Long"]],["Line1TextB",["Lat","Long"]]]'

Also make sure you use " inside the JSON, as ' is invalid.

answered Oct 3, 2015 at 17:46

Praveen Kumar Purushothaman

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1 Comment

Mohammad Ali Over a year ago

You were the first to actually post an answer (instead of comments), so picking yours as the correct answer. Thanks everyone!

Adam Mazzarella · Accepted Answer · 2015-10-03 17:54:32Z

For simplicity's sake, Javascript has two types of arrays: numeric and associative. This is similar to other languages but implemented a bit differently. In reality, arrays are really objects where numeric arrays are in an array object and associative are a plain object.

Here are the two syntaxes:

var numericArr = ['foo', 'bar', 'foobar', 42, false];
// numericArr[0] === 'foo'
// numericArr[3] === 42

var assocArr = {'type': 'foo', 'example': 'bar'};
// This can also be written as {type: 'foo'} (keys don't need quotes)
// assocArr['example'] === 'bar'

These arrays can be nested as well, like so:

var mixedArr = {data: ['foo', 'bar'], success: false};

So in your case, the named arrays will need to have curly brackets surrounding them eg.

var myStr = '[{"Line1TextA":["Lat","Long"]}, {"Line1TextB":["Lat","Long"]}]'

Notice also the quotes surrounding the array keys. You'll need that if you would like to JSON parse the data.

If you are not in a position to rewrite the data that is stored in your files, as long as it's in a consistent format you can use something like regex to do your string manipulation to correctly format the data.

Ángela · Accepted Answer · 2015-10-03 19:58:48Z

-1

You could try to use regex to place the quotes, then use JSON.parse() to parse the properly-formatted json into an array.

var myStr = '[[Line1TextA,[Lat,Long]], [Line1TextB,[Lat,Long]]]';

var json = myStr.replace(/([^\[\],\s]+)/g, '"$&"');
var array = JSON.parse(json);

Working examle: https://jsfiddle.net/397owg7q/

You might need to change the regex a bit, this only works if your data doesn't have whitespace or quotes.

answered Oct 3, 2015 at 19:58

Ángela

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1 Comment

Mohammad Ali Over a year ago

I was able to easily change the regex since I restructured the csv to begin with.

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