JavaScript Regex Test and Replace

Question

I need to sanitize some chars. I have a solution that works but I am wondering if there is a better solution that may be faster or better or if I flat out should be approaching this differently?

function escapeStr(_str){
 if (/\"|\'|\%/g.test(_str)) {
 _str = _str.replace(/"/g, "%22");
 _str = _str.replace(/'/g, "%27");
 _str = _str.replace(/%/g, "%25");
 }
 return _str;
}

And vice versa:

function unescapeStr(_str){
 if (/\%22|\%27|\%25/g.test(_str)) {
 _str = _str.replace(/\%22/g, '"');
 _str = _str.replace(/\%27/g, "'");
 _str = _str.replace(/\%25/g, "%");
 }
 return _str;
}

• abl: Why the if clause? Why not just replace, even if there are no matches?
• 200_success: Could you provide some context about what you want to accomplish? Why do you want to handle those three characters specially?
• abl: What collation? What issues? Sounds like it could be a known problem with an existing solution.
• Flambino: If it's telling you that replace is undefined, it's because you trying to use it when on a _str value that isn't a string. You can replace the test call with typeof _str === 'string', and it should work the same. The problem is: Why is _str sometimes not a string... Anyway, that's all irrelevant, since, as abl said, this sounds like a known problem
• Paul: Thanks all. I just learned that this is great place to get really good opinions and hints on my code. Much appreciated!

Answer 1

Instead of hardcoding the characters, and their escape values specifically in your .replace call, you can pass a callback function for the replacement. I suggested that you dive into encodeURI:

So, something like:

function escapeStr(_str) {
 return _str.replace(/([%'"])/g, encodeURI)
}
function unescapeStr(_str) {
 return _str.replace(/(%(?:2[257]))/g, decodeURI)
}
const e = escapeStr, u = unescapeStr;
console.log( e("string") );
console.log( e("some\" char%s") );
console.log( u("string") );
console.log( u("some%22 char%25s") );

Answer 2

In first and second function

function escapeStr(_str){
 if (/\"|\'|\%/g.test(_str)) { // unnecessary if 
 _str = _str.replace(/"/g, "%22"); // unnecessary asigment
 _str = _str.replace(/'/g, "%27"); // unnecessary asigment
 _str = _str.replace(/%/g, "%25"); // unnecessary asigment
 }
 return _str;
}

You can add if (value) this will prevent errors while passing null of something like this

This probably more complex and optimal:

const escapeStr = str => str ? str
 .replace(/%/g, "%25")
 .replace(/"/g, "%22")
 .replace(/'/g, "%27") : str
const unescapeStr = str => str ? str
 .replace(/\%25/g, "%") 
 .replace(/\%22/g, '"')
 .replace(/\%27/g, "'") : str

And if we want to go crazy use this:

const escapeStr = str => str ? str.replace(/[%'"]/g, encodeURI) : str
const unescapeStr = str => str ? str.replace(/\(%2[257])/g, decodeURI) : str
const testData = [`"hello"`,`'world'`,`2%3`,``, `xyz`, `%22hello%22`]
for (const data of testData) {
 console.log(`${data}:`)
 console.log(`escapeStr -> ${escapeStr(data)}`)
 console.log(`escapeStr -> ${unescapeStr(data)}`)
}