You can see this being used to autocomplete local JavaScript variables in http://codemirror.net/2/demo/complete.html
But,How i use this autocomplete in c language?
How i edit this code?
http://codemirror.net/demo/complete.js
Are you talking about editing the script to auto-complete C in the browser?
First you need to identify the where local variables in C are defined. You're looking for keywords like int float long or patterns like type_name identifier_1 = value, identifier_2;
The next thing you need to do is identify the function parameters. The pattern you're looking for is
return_type function_name(parm1, param2){
// current code
}
Last you need to include constants created with #define and variables defined in file scope (C) or global scope (C++).
type_name identifier = value;
#define constant value
// Outside of any sort of scope
/* something */{
}
It would be difficult to just edit the script that works on JavaScript because the two languages behave differently and have different rules. If you need some help of the ways to parse the data from C and other languages using JavaScript you might look into google-prettify which is a syntax highlighting script.
Good luck.
Related
I try something like this:
var varr = var;
varr x = 10;
It doesn't work, for obvious reasons, but you get the idea. How do I define keywords in Javascript, like how I can in C:
#define var int
var x = 10;
The above code wouldn't work, but is there a way to do something similar in Javascript? Not that I would absolutely need to, but just wondering.
var is a reserved token by Javascript and thus cannot be used incorrectly, or as part of variable names.
When JavaScript parses our code, behind the scenes it’s converting everything into appropriate characters, then the engine attempts to execute our statements in order and as var is a reserved token it will throw Uncaught SyntaxError: Unexpected token 'var'
JavaScript doesn't allow you to use the reserved keyword as the identifier's value, What you're gonna do is a pretty clear mistake here. you defined variable and assign as value unsupported datatypes which js don't know, Learn more
var <variable-name> = <reserved-keyword>
expected value:
var <variable-name> = <value>
javascript support all datatypes which you use in C, Int, Float, String, Obj...
Example of:
var x; // declare empty variable
x = 1;
var y = "String";
var z = [];
var foo = {};
The reason why this is possible in C is because #define allows you to declare macros that are replaced in the source code before compilation. Javascript doesn't have a concept of macros so it's not a part of the language however there are tools in JS that let you add this kind of compilation step even though it's not a part of JS itself.
Babel is probably the most popular way to do this and https://github.com/kentcdodds/babel-plugin-macros is pretty useful although I'm not sure if you can use it to redefine parts of the language.
You can instead use something like https://github.com/sweet-js/sweet-core to do what you want which lets you add a pre-processor step to replace macros however like I said, JS doesn't support macros so this is a step you have to execute to generate valid Javascript.
syntax varr = function (ctx) {
return #`var`;
};
varr test = 10;
$ sjs test.sweet
var test = 10;
It's also important to mention that in C this is something that's built into the language so IDEs understand how to deal with macros, but if you're using an external tool you're not going to have a fun time using macros that redefine keywords, especially when it comes to things like syntax highlighting. This is something I'd definitely discourage, but it is technically possible if you're willing to step outside the bounds of just Javascript.
I noticed that Google Closure Compiler did not rename document to something like d to reduce space.
I cannot think of a case where this would break the code (ie where document points to something else down the road). Actually the same goes for window.
Is there a reason for protecting document this way?
== EDIT ==
By renaming it I was thinking reassigning it. Example below.
var d=document;
var obj1=d.getElementById("obj1");
var obj2=d.getElementById("obj2");
... // with enough uses of document so it makes to reassign it size-wise.
Closure-compiler does not perform this "optimization" by default for the simple reason that it produces LARGER source when used with gzip. You can enable this optimization by turning on the AliasExternals pass using either the Java API or a custom build.
See https://code.google.com/p/closure-compiler/source/browse/src/com/google/javascript/jscomp/AliasExternals.java#38
What happens?
ProblemFactory's guess is correct.
This is a //TODO in the closure compiler source code. If we didn't preserve document and window and instead ran them over with d for example, at the moment the closure compiler does not know if it's overriding a global from another file. Like the comments say this will be resolved in the future at which point.
Enough words, show me the source!
If we check the closure compiler source code inside VariableReferenceCheck.java we can find the following:
private class ReferenceCheckingBehavior implements Behavior {
#Override
public void afterExitScope(NodeTraversal t, ReferenceMap referenceMap) {
// TODO(bashir) In hot-swap version this means that for global scope we
// only go through all global variables accessed in the modified file not
// all global variables. This should be fixed.
// Check all vars after finishing a scope
for (Iterator<Var> it = t.getScope().getVars(); it.hasNext();) {
Var v = it.next();
checkVar(v, referenceMap.getReferences(v).references);
}
}
If we check the hot-swap algorithm itself we can see that:
// Note we use the global scope to prevent wrong "undefined-var errors" on
// variables that are defined in other JS files.
So, we can see that this is just the closure compiler not understanding the code of globals across multiple files well enough to make that replacement. You can always do the replacement yourself :)
I think document is standardized, always-global variable. To use the same way d it has to be global also, thus global namespace will have another "junk" variable.
It could be dangerous for not aware developers (which wont be aware of that thus it is not standard variable).
I'm sure someone is going to shout at me for asking this question, but here goes: in Javascript, what is the best strategy for coping with the fact that the properties of objects are case-sensitive? If I create an object with a property called FavouriteDrink, but then I later start referring to it as favouriteDrink then I could end up in a mess.
I don't want a big library here, but is there any way to define the object so that FavouriteDrink is defined somewhere, and where in Visual Studio 2012 some intellisense will help me choose the correct property name if I can somehow contextualise the object I'm dealing with? It is only properties I'm pondering here.
Thanks.
It doesn't work this way
if i look at your your code and see :
FavouriteDrink() {}
the first thing will popup in my mind is this is a constructor function not just a normal function
and by looking at this following one
favouriteDrink() {}
i would tell that this is a normal function and i can't use it as a constructor - can't be called with new
Here is some other examples
first_name // variable
FIRST_NAME // uppercase variables shouldn't change
_first_name // local variable not intended to be used out of its scope
var FIRSTNAME = {} // name space
it’s a good idea to follow a convention as to how the words will be separated
see this Code Conventions for the JavaScript Programming Language
For the other part of your question i'm using VS 2012 and i installed JSEnhancements
and i can see all my object element
JavaScript shares the following conventions with Java and ActionScript 3.
ALL_UPPERCASE
Use this as the variable name when you define a constant, or a value that should never change.
For example, myObject.NUM_TIMES_CLICKED = 2 would be a poor candidate for a constant because it is likely to change. However, myObject.APPLE_FRENCH_SPELLING = 'pomme' would be appropriate here.
firstWordLowercaseAndTheRestAllUppercase
Use this when you are defining anything that is not a constant or a class. You would use this for most things, for example, myObject.numTimesClicked, myObject.myFunction(), myObject.returnString.
AllWordsCapitalized
Use this when you are defining a function that defines a "class," generally any function you would call with the syntax myObject.myClassInstance = new MyClass(). Notice how myClassInstance is in camel-case because it is an instance of the class. However, MyClass is all caps because it is meant to be invoked with new.
You would define the class initially like this: myObject.MyClass = function(){};
WebStorm and Sublime Text are great tools that offer the code intelligence you're looking for.
WebStorm does this out of the box, but my personal preference is Sublime Text with the SublimeCodeIntel plugin.
That being said, it's probably best for you to be using naming conventions:
UpperCamelCase is for classes
ALL_CAPS_SNAKE_CASE is for constants
lowerCamelCase is used for everything else
I am using a jQuery plugin and running it through the Microsoft Ajax Minifier. My scripts work well for me, but now I am running into an issue with this plugin. The issue is that the plugin calls a function by its name using a string:
var s = (getCachedSortType(table.config.parsers, c) == "text") ? ((order == 0) ? "sortText" : "sortTextDesc") : ((order == 0) ? "sortNumeric" : "sortNumericDesc");
Note the "sortNumeric" and "sortNumericDesc". This calls these functions:
function sortNumeric(a, b) {
return a - b;
}
function sortNumericDesc(a, b) {
return b - a;
}
This is the only location these functions are called so the IDE VS2010 doesn't think that the functions are being called from anywhere... They are conditionally via the code above.
**Here is the Problem**
When this gets minified, the string name of the function stays, but the function gets removed because it does not thing its getting referenced.
Is there any way to adjust the settings minifier to not do this?
I have also seen it change the names of the functions so
function testFunctionName(a,b)
Would become
function a
This would also cause a problem for situations like mine...
Please note, that I know it is bad code design to hard code function names like this. Like I said it is a plug-in that I am using. I would accept a solution that would call the function out right instead of by string, but I am always hesitant to modify plug-ins.
From documentation:
-evals:(ignore|immediate|safeall) specifies how eval statements are to be treated. This is an important switch to be aware of. By default Ajax Minifier will ignore any eval statements, which can break your minified code if it contains eval statements that reference named local variables or functions. This is because by default Ajax Minifier will also rename local variables and function, but it doesn’t modify the text passed to the eval function, so those references may break. If you minify code and it stops working properly, check the code for eval statements. If there are any, try specifying one of the other two –evals switch options. The “immediate” options will not rename any variables or functions within the same scope as any eval call; the “safeall” option will not rename any variables or functions not only in the same scope as any eval call, but also in any parent scopes. This will seriously impair the minification of your code, but should ensure that any calls to the eval function will work as expected. The default setting is ignoreall.
Then try -evals:immediate and if your code is still broken you have to use -evals:safeall (even if this will make your JavaScript files bigger).
UPDATE
If you're not using eval then you have to skip function renaming at all:
-rename:(all|localization|none) specifies whether or not to automatically rename local variables and functions. Global variables and functions are not automatically renamed, nor are property names. If “localization” is specified, only variables that do not start with “L_” will be renamed. The default value is all.
Just add -rename:none.
Use -unused:keep switch to retain unused functions. This, naturally, will prevent minifier from removing really unused code.
Use -rename switch to assign permanent names to functions that you call by name.
I've recently tested UglifyJS and YUI Compressor and noticed something odd.
Both minifiers don't seem to change the names of object properties, only the names of variables and functions.
for instance if I have the following code:
var objName = {first:2, second:4};
alert(objName.first + " " + objName.second);
the names first and second remain unchanged in the minified version.
Why is that?
Since in javascript a new scope is created in a function, you can scope your code in an immediately invoked function.
// scoped
(function() {
var objName = {first:2, second:4};
alert(objName.first + " " + objName.second);
})();
Then using Google's Closure Compiler, if you turn on the "Advanced" optimization it will see that the properties are only used locally, and will obfuscate them.
// result
var a={a:2,b:4};alert(a.a+" "+a.b);
It's because it doesn't know where the object is going to be used. It could be used externally by other code and you wouldn't want your other code to have to change whenever you obfuscate it.
Edit So basically, it's like that to prevent obfuscation from breaking external/internal references to properties that may not be possible to figure out while obfuscating.
Since there are no well defined scoping rules around objects in JavaScript it's impossible to obfuscate the names in a way that is guaranteed to be correct.
For example, if you had the following function:
function f() {
return { first: 'foo', second: 'bar' };
}
In order to obfuscate the property names you would have to nail down all the places that f is called from. Since functions are first-class in JavaScript they can be assigned and passed around in arbitrary ways making it impossible to pin down where f is referenced without actually running the program.
Additionally, JavaScript doesn't have any way for you to specify intent around what's public API and what isn't. Even if the minimizer could reliably determine where the function is called from in the code you give it, there would be no way for it to make the same changes to code that it hasn't seen.
I guess that's because the minifiers would break the object properties. Consider this:
function getProp(ob,name) {
return ob[name];
}
var objName = {first: 2, second: 4};
var prop = getProp(objName, "second");
There's no way for the minifier to know the string literal "second" being an object property. The minified code could look like this then:
function a(b,c){return b[c]}var d={p1:2,p2:4};var e=a(d,"second")
Broken now.
The latest release of uglify (today) has object property mangling, see v2.4.19. It also supports reserved files for excluding both object properties and variables that you don't want mangled. Check it out.
The only public tool so far to obfuscate property and function names (afaik) is the Closure Compiler's Advanced mode. There are a lot of limitations and restrictions, but the end result is generally worth it.
As a passing note: the Dojo Toolkit is compatible (with some minor modifications) with the Closure Compiler in Advanced mode -- arguably the only large-scale public JavaScript library that can be fully obfuscated. So if you are looking at obfuscation to protect your IP, you should look into using Dojo for the task.
http://dojo-toolkit.33424.n3.nabble.com/file/n2636749/Using_the_Dojo_Toolkit_with_the_Closure_Compiler.pdf?by-user=t
Stephen
What about doing something like:
// scoped
(function() {
var objName = {first:2, second:4};
var vA = 'first';
var vB = 'second';
alert(objName[vA] + " " + objName[vB]);
})();
Once objName.first and/or objName.second are referenced enough times, this technique will start to save characters. I can't think of any reason that wouldn't work, but I can't find any minifiers that do it.