I want to strip certain characters from a textarea - PHP/Javascript

Question

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The Details

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I have a simple textarea <textarea></textarea>

The value of this textarea is sent through ajax and stored in a database.

The value in this database is viewed on an iPad (or iPad mini or iPhone, etc)

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The Problem

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When someone copies text from somewhere (could be anywhere from the internet potentially), I want to remove any weird characters such as: “windows-1252 quotes” from the text before storing them in a utf8_unicode_ci column in a database. This column stores the above quotes but are unknown on certain devices (like iPad)

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The Question

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How can I remove these characters in Javascript or PHP?

string.replace has been tried from various examples to remove these characters.

htmlentities($sample) has been tried in order to convert these characters but still no luck.

Any help would be appreciated! Thanks!

Answer 1

Regular expressions will do this; php's function for this is preg_replace, javascript's is simply .replace(). You can find usage snippets everywhere ;)

There are two ways to approach this using regex:

1. Define an allowed character range and strip anything that isn't in that range.

[^\w-=+()!@#$%^*(] will match NOT anything in this character range (the ^ at the beginning of the character class denotes this). You can then take the resulting matched characters and replace with an empty string.

Working example: http://regex101.com/r/zK2qW6

2. Define a non-allowed character range and strip anything that is in that range.

[“”] will match anything in this character range. You can then take the resulting matched characters, and again replace with an empty string. You could also use a regex unicode range here too.

Working example: http://regex101.com/r/yG4qJ4

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In the end, you should choose the path which requires the smallest expression. If there's only a handful of characters to replace, use option #2. If you only want to allow a handful of characters, use option #1.