slashes

Add or strip backslashes.

Provides two methods, add and strip which are almost the same as PHP's addslashes and stripslashes functions respectively.

The add method will prefix backslash (\), double quote ("), and single quote (') characters with backslashes. Null (\0) characters will be replaced with backslash zero "\\0", and newline (\n) characters will be replaced with "\\n". The newline replacement differs from PHP because JavaScript has ASI (auto semicolon insertion) at the end of each line, so a newline in a JavaScript string literal does not preserve the newline character correctly.

The strip method replaces all sequences of two characters that start with a backslash, with the second character in the sequence. There are three caveats. A single non-escaped slash at the end of the string will be removed. Backslash zero "\\0" will become a null (\0) character. Backslash 'n' "\\n" will become a newline (\n) character.

The goal of this utility is to make a string safe for concatenation or injection into JavaScript source.

var foo = "\\bar";
var source = "console.log('" + bar + "');";
eval(source);

You might expect the above snippet to output \bar but instead you will see ar, because the source string ends up being console.log('\bar'); which is interpreted as starting with an escaped "b" rather than a backslash and then a "b". It can be fixed using the add method.

var foo = "\\bar";
var source = "console.log('" + slashes.add(bar) + "');";
eval(source);

Now the source comes out as console.log('\\bar'); and the output will be \bar.

Install

npm install slashes --save

Usage

slashes.add(string, [number])
slashes.strip(string, [number])

If a non-string value is passed as the first parameter, it will be coerced to a string.

If a non-number is passed as the second parameter, it will be coerced to a number. Negative numbers are equivalent to their positive counter parts. Zero is the same as one.

Examples

var slashes = require('slashes');

var test = "'test'\n\"ing\"\0";
var added = slashes.add(test);
var stripped = slashes.strip(added);

console.log("test:\n%s\n", test);
console.log("added:\n%s\n", added);
console.log("stripped:\n%s\n", stripped);

Output should be...

test:
'test'
"ing"

added:
\'test\'
\"ing\"\0

stripped:
'test'
"ing"

Both methods also take an optional second number parameter, 1 or greater. This is equivalent to calling the method that many times.

slashes.add(string, 2);
// ...is the same as...
slashes.add(slashes.add(string));

slashes.strip(string, 2);
// ...is the same as...
slashes.strip(slashes.strip(string));

Note that in JavaScript, "\0" and "\u0000" are identical. The add method will convert both to "\\0".