Moi aussi, j'ai eu un problème avec ça. Et après un certain temps à chercher la réponse et à regarder toutes les réponses de tout le monde, je pense que j'ai trouvé une solution viable à cela.
Il semble que la plupart des réponses que j'ai rencontrées utilisent des fonctions pour contenir les constantes. Comme de nombreux utilisateurs des nombreux forums le mentionnent, les fonctions peuvent être facilement écrasées par les utilisateurs côté client. J'ai été intrigué par la réponse de Keith Evetts selon laquelle l'objet constantes n'est pas accessible par l'extérieur, mais uniquement par les fonctions à l'intérieur.
J'ai donc trouvé cette solution:
Mettez tout à l'intérieur d'une fonction anonyme afin que les variables, les objets, etc. ne puissent pas être modifiés par le client. Masquez également les fonctions «réelles» en faisant en sorte que d'autres fonctions appellent les fonctions «réelles» de l'intérieur. J'ai également pensé à utiliser des fonctions pour vérifier si une fonction a été modifiée par un utilisateur côté client. Si les fonctions ont été modifiées, modifiez-les à nouveau à l'aide de variables qui sont «protégées» à l'intérieur et ne peuvent pas être modifiées.
/*Tested in: IE 9.0.8; Firefox 14.0.1; Chrome 20.0.1180.60 m; Not Tested in Safari*/
(function(){
/*The two functions _define and _access are from Keith Evetts 2009 License: LGPL (SETCONST and CONST).
They're the same just as he did them, the only things I changed are the variable names and the text
of the error messages.
*/
//object literal to hold the constants
var j = {};
/*Global function _define(String h, mixed m). I named it define to mimic the way PHP 'defines' constants.
The argument 'h' is the name of the const and has to be a string, 'm' is the value of the const and has
to exist. If there is already a property with the same name in the object holder, then we throw an error.
If not, we add the property and set the value to it. This is a 'hidden' function and the user doesn't
see any of your coding call this function. You call the _makeDef() in your code and that function calls
this function. - You can change the error messages to whatever you want them to say.
*/
self._define = function(h,m) {
if (typeof h !== 'string') { throw new Error('I don\'t know what to do.'); }
if (!m) { throw new Error('I don\'t know what to do.'); }
else if ((h in j) ) { throw new Error('We have a problem!'); }
else {
j[h] = m;
return true;
}
};
/*Global function _makeDef(String t, mixed y). I named it makeDef because we 'make the define' with this
function. The argument 't' is the name of the const and doesn't need to be all caps because I set it
to upper case within the function, 'y' is the value of the value of the const and has to exist. I
make different variables to make it harder for a user to figure out whats going on. We then call the
_define function with the two new variables. You call this function in your code to set the constant.
You can change the error message to whatever you want it to say.
*/
self._makeDef = function(t, y) {
if(!y) { throw new Error('I don\'t know what to do.'); return false; }
q = t.toUpperCase();
w = y;
_define(q, w);
};
/*Global function _getDef(String s). I named it getDef because we 'get the define' with this function. The
argument 's' is the name of the const and doesn't need to be all capse because I set it to upper case
within the function. I make a different variable to make it harder for a user to figure out whats going
on. The function returns the _access function call. I pass the new variable and the original string
along to the _access function. I do this because if a user is trying to get the value of something, if
there is an error the argument doesn't get displayed with upper case in the error message. You call this
function in your code to get the constant.
*/
self._getDef = function(s) {
z = s.toUpperCase();
return _access(z, s);
};
/*Global function _access(String g, String f). I named it access because we 'access' the constant through
this function. The argument 'g' is the name of the const and its all upper case, 'f' is also the name
of the const, but its the original string that was passed to the _getDef() function. If there is an
error, the original string, 'f', is displayed. This makes it harder for a user to figure out how the
constants are being stored. If there is a property with the same name in the object holder, we return
the constant value. If not, we check if the 'f' variable exists, if not, set it to the value of 'g' and
throw an error. This is a 'hidden' function and the user doesn't see any of your coding call this
function. You call the _getDef() function in your code and that function calls this function.
You can change the error messages to whatever you want them to say.
*/
self._access = function(g, f) {
if (typeof g !== 'string') { throw new Error('I don\'t know what to do.'); }
if ( g in j ) { return j[g]; }
else { if(!f) { f = g; } throw new Error('I don\'t know what to do. I have no idea what \''+f+'\' is.'); }
};
/*The four variables below are private and cannot be accessed from the outside script except for the
functions inside this anonymous function. These variables are strings of the four above functions and
will be used by the all-dreaded eval() function to set them back to their original if any of them should
be changed by a user trying to hack your code.
*/
var _define_func_string = "function(h,m) {"+" if (typeof h !== 'string') { throw new Error('I don\\'t know what to do.'); }"+" if (!m) { throw new Error('I don\\'t know what to do.'); }"+" else if ((h in j) ) { throw new Error('We have a problem!'); }"+" else {"+" j[h] = m;"+" return true;"+" }"+" }";
var _makeDef_func_string = "function(t, y) {"+" if(!y) { throw new Error('I don\\'t know what to do.'); return false; }"+" q = t.toUpperCase();"+" w = y;"+" _define(q, w);"+" }";
var _getDef_func_string = "function(s) {"+" z = s.toUpperCase();"+" return _access(z, s);"+" }";
var _access_func_string = "function(g, f) {"+" if (typeof g !== 'string') { throw new Error('I don\\'t know what to do.'); }"+" if ( g in j ) { return j[g]; }"+" else { if(!f) { f = g; } throw new Error('I don\\'t know what to do. I have no idea what \\''+f+'\\' is.'); }"+" }";
/*Global function _doFunctionCheck(String u). I named it doFunctionCheck because we're 'checking the functions'
The argument 'u' is the name of any of the four above function names you want to check. This function will
check if a specific line of code is inside a given function. If it is, then we do nothing, if not, then
we use the eval() function to set the function back to its original coding using the function string
variables above. This function will also throw an error depending upon the doError variable being set to true
This is a 'hidden' function and the user doesn't see any of your coding call this function. You call the
doCodeCheck() function and that function calls this function. - You can change the error messages to
whatever you want them to say.
*/
self._doFunctionCheck = function(u) {
var errMsg = 'We have a BIG problem! You\'ve changed my code.';
var doError = true;
d = u;
switch(d.toLowerCase())
{
case "_getdef":
if(_getDef.toString().indexOf("z = s.toUpperCase();") != -1) { /*do nothing*/ }
else { eval("_getDef = "+_getDef_func_string); if(doError === true) { throw new Error(errMsg); } }
break;
case "_makedef":
if(_makeDef.toString().indexOf("q = t.toUpperCase();") != -1) { /*do nothing*/ }
else { eval("_makeDef = "+_makeDef_func_string); if(doError === true) { throw new Error(errMsg); } }
break;
case "_define":
if(_define.toString().indexOf("else if((h in j) ) {") != -1) { /*do nothing*/ }
else { eval("_define = "+_define_func_string); if(doError === true) { throw new Error(errMsg); } }
break;
case "_access":
if(_access.toString().indexOf("else { if(!f) { f = g; }") != -1) { /*do nothing*/ }
else { eval("_access = "+_access_func_string); if(doError === true) { throw new Error(errMsg); } }
break;
default:
if(doError === true) { throw new Error('I don\'t know what to do.'); }
}
};
/*Global function _doCodeCheck(String v). I named it doCodeCheck because we're 'doing a code check'. The argument
'v' is the name of one of the first four functions in this script that you want to check. I make a different
variable to make it harder for a user to figure out whats going on. You call this function in your code to check
if any of the functions has been changed by the user.
*/
self._doCodeCheck = function(v) {
l = v;
_doFunctionCheck(l);
};
}())
Il semble également que la sécurité soit vraiment un problème et il n'y a aucun moyen de «cacher» votre programmation du côté client. Une bonne idée pour moi est de compresser votre code afin qu'il soit vraiment difficile pour quiconque, y compris vous, le programmeur, de le lire et de le comprendre. Il existe un site sur lequel vous pouvez vous rendre: http://javascriptcompressor.com/ . (Ce n'est pas mon site, ne vous inquiétez pas, je ne fais pas de publicité.) C'est un site qui vous permettra de compresser et d'obscurcir du code Javascript gratuitement.
- Copiez tout le code du script ci-dessus et collez-le dans la zone de texte supérieure de la page javascriptcompressor.com.
- Cochez la case Base62 encode, cochez la case Shrink Variables.
- Appuyez sur le bouton Compress.
- Collez et enregistrez le tout dans un fichier .js et ajoutez-le à votre page en tête de votre page.
Chrome
vous permet d'utiliser le mot-cléconst
pour utiliser des constantes. par exempleconst ASDF = "asdf"
. Cependant, comme ilconst
n'est pas compatible avec plusieurs navigateurs, je m'en tiens généralement à unevar
déclaration.