I'm seeking to understand the distinctions between JavaScript's String.slice() method and PHP's mb_substr function. As a front-end developer, I encountered a challenging issue that affected our production environment and highlighted the differences between these two functions.
Here's the context: For a feature requiring text to be truncated to 25 characters before submission to our server (due to length constraints), I implemented the JavaScript text.slice(0, 25) method. It seemed straightforward enough, until complaints from users began flooding in the following day. It turns out emojis within the text were causing unexpected issues.
To illustrate, consider the following JavaScript example:
const text = 'A Marketing post ';
console.log(text.slice(0, 25));
// Result: A Marketing post �
console.log(JSON.stringify(text.slice(0, 25)))
// Result: "A Marketing post \ud83d"
The issue arises when the emoji is split, resulting in broken text represented by \uD83D, a scenario I wasn't prepared to handle. Consequently, this led to runtime errors on our PHP backend, though I'm unsure of the specifics.
In an attempt to address this, the backend switched to using mb_substr, like so:
<?php
echo mb_substr('A Marketing post ', 0, 25);
// Outputs: 'A Marketing post '
This method didn't break the emojis or result in strange character representations, despite not always precisely cutting off at 25 characters.
Given this experience, I'm eager to learn about the fundamental differences between JavaScript's String.slice() and PHP's mb_substr. My goal is to better align the frontend implementation with the backend's mb_substr handling, ensuring consistent treatment of strings across our tech stack.