Joining array elements with a regex

Question

Is it possible to join array elements with a regex? If so, how do I achieve these requirements?

Every element should be joined with a spacing character unless it is an empty element.
Empty array elements should be joined with a new line character (\n).

That means that this:

["Hello, this is a sentence.", "This is another sentence.", "", "", "Then, there are 2 new lines.","","Then just one new line."]

Should be converted with .join to this:

Hello, this is a sentence. This is another sentence.

Then, there are 2 new lines.
Then just one new line.

Ricardo Lohmann · Accepted Answer · 2012-06-25 18:06:42Z

1

var string = "";

for(var index = 0; index < elements.length; index++) {
    var lastElement = elements[index -1];
    string += elements[index] !== "" ? (lastElement && lastElement !== ""? " " + elements[index] : elements[index]) : "\n";
}
console.log(string);

DEMO

edited Jun 25, 2012 at 18:06

answered Jun 25, 2012 at 17:33

Ricardo Lohmann

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5 Comments

Andres SK Over a year ago

almost worked fine. i still don't know why is it adding a space character at the beginning of all sentences.

Ricardo Lohmann Over a year ago

@andufo Sorry, I didn't see it. Fixed.

Andres SK Over a year ago

still has some issues when the sentences are joined without newlines between them, but you gave me the main idea. i'll try to take it from there. thanks!

Andres SK Over a year ago

i had to accept @kevin-b 's answer, it covered all the spacing issues between sentences as well.

Andres SK Over a year ago

worked fine this time, with less code. i just had to add a $.trim(string) to get rid of the last space character. thanks!

user400654 · Accepted Answer · 2012-06-25 17:41:40Z

1

Loop through the array replacing empty elements with <br /> or \n depending on where you are using the string, then join it on "".

for (var i = 0; i < myArr.length; i++) {
    myArr[i] = myArr[i] === "" ? "\n" : myArr[i];
}
var myStr = myArr.join("");

Edit: here's a full demo with your additional requirements: http://jsfiddle.net/auAAH/

var myArr = ["Hello, this is a sentence.", "This is another sentence.", "", "", "Then, there are 2 new lines.", "", "Then just one new line."];
for (var i = 0; i < myArr.length; i++) {
    if (myArr[i] === "") {
        myArr[i] = "\n";
        if (i !== 0 && myArr[i - 1] !== "\n") {
            myArr[i - 1] = myArr[i - 1].replace(/ $/, "");
        }
    }
    else if (i < myArr.length-1) {
     myArr[i] = myArr[i] + " ";   
    }
}
var myStr = myArr.join("");
document.getElementsByTagName("textarea")[0].value = myStr;

edited Jun 25, 2012 at 17:41

answered Jun 25, 2012 at 17:25

user400654

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2 Comments

Andres SK Over a year ago

I'm using it on a textarea. I have to join them with a space character, else the sentences will have no spacing between them. I also don't want unnecessary spaces in newlines.

user400654 Over a year ago

Either way all of the changes will need to be done in a loop of some kind.

Andrew Kozak · Accepted Answer · 2012-06-25 17:26:37Z

0

You should first use a match/replace loop to modify the elements according to your rules, and then you should .join the resulting array.

answered Jun 25, 2012 at 17:26

Andrew Kozak

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