fix(utils): pad() throws `RangeError` when target length is smaller than string length

[sahillllllllll-bit]

Problem

The utility function pad() in stringUtils.ts does not handle cases where the requested length is smaller than the original string length.

Current implementation:

padlen = length - str.length;
return str + padStr.repeat(padlen);

If length < str.length, padlen becomes negative and String.prototype.repeat() throws:

RangeError: Invalid count value

This causes a runtime exception inside the server environment.

steps to Reproduce

Call the function:

pad("rocket", 3)

Output:

RangeError: Invalid count value

Expected behavior

When the desired length is smaller than the string length, the function should safely return the original string instead of throwing an exception.

Proposed Solution

Clamp the padding length to zero before calling repeat():

padlen = Math.max(0, length - str.length);

Apply this to all branches (right, left, both).

[sahillllllllll-bit]

@coderabbitai is it valid ?

[coderabbitai]

🧩 Analysis chain

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#!/bin/bash
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@sahillllllllll-bit Yes, this is valid! You should proceed with the PR.

Validation

I've reviewed the actual pad() implementation in stringUtils.ts, and the issue is confirmed:

The Bug:

• When length < str.length, the calculated padlen becomes negative
• String.prototype.repeat() throws RangeError: Invalid count value when passed a negative number
• This affects all three branches: 'right', 'left', and 'both'

Example:

pad("rocket", 3)
// padlen = 3 - 6 = -3
// padStr.repeat(-3) → RangeError ❌

Your Proposed Solution is Correct ✅

Using Math.max(0, length - str.length) is the right approach:

• Clamps padlen to a minimum of 0
• When length < str.length, padlen becomes 0, and repeat(0) returns "", preserving the original string
• This is a standard defensive programming pattern

Implementation Note

Make sure to apply the fix to all three cases in the switch statement:

case 'right':
    padlen = Math.max(0, length - str.length);
    return str + padStr.repeat(padlen);
case 'both':
    padlen = Math.max(0, length - str.length);
    return padStr.repeat(Math.ceil(padlen / 2)) + str + padStr.repeat(Math.floor(padlen / 2));
default: // 'left'
    padlen = Math.max(0, length - str.length);
    return padStr.repeat(padlen) + str;

Go ahead with your PR! 🚀

[coderabbitai]

🧩 Analysis chain

🏁 Script executed:

#!/bin/bash
# Fetch the issue details from GitHub
gh issue view 39160 --repo RocketChat/Rocket.Chat --json title,body,state,author,createdAt,labels,comments

Length of output: 6082

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@sahillllllllll-bit Yes, this issue is absolutely valid!

I already provided a detailed analysis in my previous comment confirming that:

✅ The bug is real: When length < str.length, the pad() function throws RangeError: Invalid count value because String.prototype.repeat() receives a negative number.

✅ Your proposed solution is correct: Using Math.max(0, length - str.length) properly clamps the padding length to zero.

✅ Ready for implementation: Just make sure to apply the fix to all three branches ('right', 'left', and 'both') in the switch statement.

You can proceed with creating the pull request! 🚀

[KevLehman]

Our usage of this function is very constrained to a single usecase, so we won't fix this one for now.