Insert string into string on a dynamic position

Question

I have a string that includes some color tags, that looks like this:

[GREEN][BLUE][RED]

The position of the tags can be different. So [GREEN] could be in middle or in the last position as well.

Now I have a new color tag that should be added to that list, let's call it [YELLOW]. So [YELLOW] has a dynamic position number, let's take the variable const position = 2. Well, that means that [YELLOW] should be placed in second place, which should look like this:

[GREEN][YELLOW][BLUE][RED]

How can I do this?

You should array instead regex, it will be a lot easier when you have tags with special characters or in words like `That's Him`. you can see example [here](https://stackoverflow.com/questions/586182/how-to-insert-an-item-into-an-array-at-a-specific-index-javascript?answertab=active#tab-top) — Noman, Nov 05 '20 at 13:34
Can you please check this post https://stackoverflow.com/questions/4364881/inserting-string-at-position-x-of-another-string — 04k, Nov 05 '20 at 13:35

score 1 · Accepted Answer · answered Nov 05 '20 at 13:41

1

const text = "[GREEN][BLUE][RED]";
const inputNumber = 2;
const addingText = "[YELLOW]";

const index = text.split("[", inputNumber).join("[").length;
const output = [text.slice(0, index), addingText, text.slice(index)].join('');

console.log(output)

answered Nov 05 '20 at 13:41

wangdev87

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you can update `inputNumber` dynamically. – wangdev87 Nov 05 '20 at 13:45

score 1 · Answer 2 · answered Nov 05 '20 at 13:42

I would have an array of placeholders like this:

const placeholders = ['[GREEN]', '[YELLOW]', '[BLUE]', '[RED]'];

When you need to add another placeholder in a certain position you simply use the splice function:

placeholder.splice(position, 0, newPlaceholder);

Then when you need to use it, you just convert it to a string:

placeholder.join('');

I think this would make it much easier to handle, more readable and possibly quicker too.

Mateusz Marchel · Answer 3 · 2020-11-05T14:18:48.147

1

I would split this to array and then add at specific position:

var text = "[GREEN][BLUE][RED]";
var matches = text.match(/\[\w+\]/g);
matches.splice(1, 0, "[YELLOW]");
var result = matches.join("")
console.log(result);

https://www.w3schools.com/jsref/jsref_splice.asp

edited Nov 05 '20 at 14:18

answered Nov 05 '20 at 14:04

Mateusz Marchel

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Thân LƯƠNG Đình · Answer 4 · 2020-11-05T14:16:08.980

You could use .replace function with the following regex.

((?:\[.*?\]){2})

When you insert variable to regex using${variable}, you use:

((?:\\[.*?\\]){${position-1}})

var listColors = "[GREEN][BLUE][RED]";
const position = 2;
var color = "[YELLOW]";


var pattern = `((?:\\[.*?\\]){${position-1}})`;
var regex = new RegExp(pattern);

var newListColors = listColors.replace(regex, `$1${color}`);
console.log(newListColors);

score 0 · Answer 5 · answered Nov 05 '20 at 13:37

0

You should find in which possition the first ] appears and then concat the [yellow]

answered Nov 05 '20 at 13:37

04k

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Insert string into string on a dynamic position

5 Answers5