JSON why are forward slashes escaped

Question

The reason for this  escapes  me   JSON escapes the forward slash  so a hash  a   a b c   is serialized as   a   a  b  c   instead of   a   a b c     Why

User · Answer

The JSON spec says you CAN escape forward slash  but you don t have to

User · Answer

I asked the same question some time ago and had to answer it myself  Here s what I came up with      It seems  my first thought  that it comes from its JavaScript   roots  was correct                    in JavaScript  and JSON is valid JavaScript  However    why are the other ignored escapes  like  z  not allowed in JSON       The key for this was reading   http   www cs tut fi  jkorpela www revsol html  followed by   http   www w3 org TR html4 appendix notes html h-B 3 2  The feature of   the slash escape allows JSON to be embedded in HTML  as SGML  and XML

User · Answer

JSON doesn t require you to do that  it allows you to do that  It also allows you to use   u0061  for  A   but it s not required  Allowing    helps when embedding JSON in a  lt script gt  tag  which doesn t allow  lt   inside strings  like Seb points out   Some of Microsoft s ASP NET Ajax JSON API s use this loophole to add extra information  e g   a datetime will be sent as    Date milliseconds       Yuck

User · Answer

Ugly PHP   The JSON UNESCAPED UNICODE JSON UNESCAPED SLASHES must be default  not an  strange  option    How to say it to php-developers   The default MUST be the most frequent use  and the  current  most widely used standards as UTF8  How many PHP-code fragments in the Github or other place need this exoctic  embedded in HTML  feature

User · Answer

PHP escapes forward slashes by default which is probably why this appears so commonly  I m not sure why  but possibly because embedding the string   lt  script gt   inside a  lt script gt  tag is considered unsafe   This functionality can be disabled by passing in the JSON UNESCAPED SLASHES flag but most developers will not use this since the original result is already valid JSON

[javascript] JSON: why are forward slashes escaped?

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