Posts by mgibsonbr • 80,631 points
861 posts
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9
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viewsA: How to replace a certain string within another string in Javascript?
Replacing specific positions To replace only a fixed position or range, just use substring. First take the chunk from the beginning to the starting position you want to replace, then the chunk that…
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answers2271
viewsA: How do you really learn how to use Javascript promises?
In reality, if your program is well structured the form of reasoning ("first this happens and then it has to happen that") is not so different. Imagine a function like: function f() { var x =…
javascriptanswered mgibsonbr 80,631 -
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answers1067
viewsA: Is there a problem using Unicode characters for code identifiers?
When it comes to using syntactic elements in general (and not just identifiers) that go beyond ASCII, there are a number of factors to consider: The compiler needs to offer appropriate support for…
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answer261
viewsA: Optimize the collision between particles
For a simple optimization that doesn’t require much change in code, I have three suggestions: You are testing all the particles against all the other two times (i.e. i of [0,n] vs j of [0,n]). Test…
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answers7464
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answers672
viewsA: Event fires second only, after sequence of user actions
Most likely your problem is in blur. Follow the following steps: click on any box so that it turns orange click on one of the command buttons 2.1. transfer focus to another place (click another…
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answers110
viewsA: String assembler (or How to improve the performance of massive replacements)
In Javascript, strings are immutable. This means that - whenever you try to do a string substitution - a new string will be created with the result. This makes it particularly problematic to…
javascriptanswered mgibsonbr 80,631 -
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answers2180
viewsA: Generating a pseudo-random number based on an input
The simplest solution I can offer is to simply use a hash function - like MD5 (or something more sophisticated - although I believe in your case it is more important that the function is quick).…
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answer1489
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answer802
viewsA: How to link the Forms created in Django to the forms already created in the HTML template?
As explained in this section of the documentation, you do not need to use the automatic form generation method ({{ form.as_p }}) if you don’t want to. Just have the fields in your template input…
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answer4798
viewsA: Select fields from another table with multiple foreign keys
Just make a join normal, giving names (aliases) for the tables consulted and - on the return of the select - referencing the specific tables and also giving names to them: select g.IDgestao as…
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answer655
viewsQ: Alternatives to the (anti-)standard Entity-Attribute-Value
I am working on two systems that have a common feature: entities whose attributes are dynamic (i.e. cannot be "plastered" - hardcoded), need to be consulted in search operations (result filter), but…
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answer1097
viewsA: How to lock keyboard in jquery?
For security reasons, no browser will allow any page to take away from the user the most basic controls - such as minimizing the window, switching to another one, etc. Nothing prevents, for example,…
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answers1225
viewsA: Mysql Transaction When? How? Why?
I will give you a partial answer, because I also do not know in detail how transactions work (whether in Mysql or any other bank): First of all, do not confuse isolation with lock. The first is to…
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answers1664
viewsA: How to create a plugin for jQuery’s $() function
Background jQuery specializes in dealing with elements of DOM. When you do something like: var x = $("seletor") It creates an object that contains - among other things - a list of zero or more…
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answer1126
viewsA: How to change values of an Enum within the code itself?
Every time you change something in Swing (or AWT) that requires a new rendering, you need to call the method repaint for the component to "paint" again. In other words, the method paint is not…
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answers471
viewsA: Factorial series from thehuxley.com site
Your problem is that both the return of fatorial as to the count are integers. In Python 2, when an integer is divided by another, the result is always an integer: >>> 3/2 1 >>>…
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answers99
viewsQ: How to get the code from a Unicode General Category?
Java has the method Character.getType(char) to obtain the Category General Unicode of a character, but the return value is a int - corresponding to a constant defined in the class itself Character…
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answers6863
viewsA: Capturing audio over the microphone via Javascript or HTML
This can be done through Media Capture and Streams, when supported (Firefox, Chrome, and Opera support; Internet Explorer, I’m afraid not yet). First, look for the function getUserMedia (some…
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answers1436
viewsA: How does method management work in C#memory?
I cannot speak specifically of the CLR, but the reasoning must be the same: every time you define a class, that class is represented in memory in some way. There is a single representation for this…
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answer241
viewsA: Conflicts between double tap and click. (jQuery and Hammer.js)
Your problem is that the setTimeout is called twice: once in the first click/slap and once in the second. What is being returned on the console is natural: 1) the first is detected, prints false and…
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answers5450
viewsA: How to write easy-to-maintain, readable code?
1. Concision As a rule, the smaller the code the better. Your decision to use higher level functions is, in my opinion, correct: at the same time it is clear what its commands do in general (All:…
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answers654
viewsA: Problem decrypting hash in Base64
That’s not how the .htpasswd works... What is stored is not the coded password on base 64, but rather a password hash - and to my knowledge, this is not necessarily encoded in base 64 (it can…
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answers182
viewsA: Doubt about constant-time sorting algorithms
I can’t give you a rigid mathematical test, but I say with certainty that what is asked is impossible. For any case not trivial: k < 0 (only admits the empty vector with input, the return is…
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answers573
viewsA: Why are you wearing shorts?
To maniero’s response already gives an excellent overview, I would just like to complement the following part: The most common if you have a very large volume of data that needs to be manipulated…
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answer966
viewsA: How to implement the six degree separation theory algorithm?
This problem can not only be solved with classic algorithms from graph theory, how there are already ready implementations in several languages, including C#. First, consider that your data mass…
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answers1927
viewsA: Why is multiplication faster than division?
There are several efficient algorithms to perform - in binary - multiplication (eg.: Dadda Multiplier, Wallace Tree) and the division (ex.: Newton-Raphson, Goldschmidt). Often they [at least…
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answer610
viewsA: How to encode an array of bytes (string) in another database in order to represent the result with the characters of A-Z and 0-9 in Delphi?
As already quoted, in the general case this problem is impossible: no compression algorithm has positive performance in the average case (The Pigeon House Principle), and by restricting which…
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answer1506
viewsA: Disable keyboard in some fields
For this it is enough that, in the text fields, you prevent the propagation event - so that the generic code does not act on it. Also, it is better to deal with the keydown instead of the keyup…
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answers10198
viewsA: What are lexical scope and dynamic scope and what are their main differences?
The scope of a variable determines in which parts of the program this variable can be accessed. The simplest (and best known) example of the scope is the global scope and the local scope: var x =…
answered mgibsonbr 80,631 -
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answers204
viewsA: How to split a string in PHP?
I don’t know if it’s the best way, but one way would be to use a regular expression: ^.*?btih\:([^&]+).*?tr\=([^&]+).*$ Detailing: ^ - string start .*? - followed by anything (lazy…
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answer452
viewsA: Know the most repetitive code in a data structure (list)
Your problem is that you have a single variable (cont) which is incremented every time two codes are equal. Every time any codes are the same. If the code a repeat 10 times and the b repeat 2 times,…
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answers19793
viewsA: Functional Programming and Object-Oriented Programming. What are they and what are their main differences?
In theory, comparing these two paradigms makes no sense: the functional programming, to imperative programming and the logic programming (among others) refer to the way a given computation is…
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answers1331
viewsA: Ruby - What’s the difference if you use two dots or quotes in a string?
When creating a string using :string, that string is only throughout the program, i.e. the system checks if a string already exists with these characters, and if it exists it reuses it instead of…
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answers1455
viewsA: How to find special characters that are inside other characters using javascript
As Brasofilo said in the comments, the ideal is to prevent this wrong string from entering JSON first. Dealing with the problem after the fact is much harder... If your JSON has exactly this format,…
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answer240
viewsA: Acquiring Javascript coordinates with the help of the Camanjs library
How Camanjs himself creates a canvas With your image, it’s not necessary to create another one - it just brings additional complication. I suggest using the canvas itself and drawing on top - right…
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answers1124
viewsA: Difficulty with the javascript "find and replace" function for a browser application
I’m assuming you’re familiar with the syntax of Javascript, if you know as a switch and case works. If I’m wrong, I suggest starting with a Javascript tutorial, or maybe asking a more specific…
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answers177
viewsQ: Should I take any action regarding Heartbleed?
As a developer, I have to take some action regarding the Heartbleed? Being a problem in Openssl, I believe it is more within the scope of webmasters, server administrators, etc. But I’m not sure if…
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answer683
viewsA: Get cookies from an Httpclient login on android
For this you can use HttpContext. Assign a CookieStore to the context and pass along with the HttpPost in the method execute. Example: (Complete code here) // Cria uma instância local do cookie…
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answers527
viewsA: My website was cloned?
Although the question is not about development, and difficult to answer in the absence of more details, I will try to give an answer. First of all, if you created the store "based on the knowledge…
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answers4053
viewsA: Is it wrong to use class inheritance to group common behaviors and attributes?
Answering your main question: there are situations where it would be appropriate to simply use inheritance to group objects with common behaviors and attributes? Rather, a comment: "having common…
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answers6692
viewsA: How to make the textarea automatically increase height to a certain limit?
Whenever the textarea is edited by any means (keyboard, mouse, Ctrl+V, etc), check that your screen size is smaller than your actual content (i.e. the content being served by the scrollbar) and,…
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answers7844
viewsA: How can I get the id in classes with equal names?
When you have a selector that returns more than one element, and you call the method html in it, it only returns the result of the first element. Several functions of jQuery work the same way. If…
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answers664
viewsA: How to effect "cascade" with Javascript / jQuery?
For a better and more concise solution, see the response of @Sergio. I’d use a simple setInterval: var indice = 0; var interval = setInterval(function() { var proximo = $("li").eq(indice++); if (…
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answer565
viewsA: Find in an array the next value greater than a predefined value
You will hardly get a better solution than testing value to value. A complete pass on the list is O(n), and that’s the limit you can reach - because in the worst case (i.e. the value you want does…
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answers222
viewsA: Return null by breaking the code
You can only call a method in the variable umaPessoa if its value is not zero - inclusive umaPessoa.equals(null). The correct way to compare a variable to null is by using the (des)equality operator…
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answer402
viewsA: Is it true (yet?) that each Tor router maintains a connection with each other router? Why?
The fact that each "Relay" node has to connect to any other node of this type does not mean that the connections need stay open 100% of the time - just while they’re being used. I don’t know the…
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answers11874
viewsA: How to create an infinite array?
In Java arrays have fixed size, specified in creation. If you need to store more elements that fit in the array, your only output is to create a new, larger array and copy the existing elements to…
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answers864
viewsA: How to set Background-image with SVG hosted elsewhere
According to the Validator.W3.org there are two problems with the files your server is sending: The charset of the document is not specified; The Mime Type is incorrect (it is returning text/xml…
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answers2309
viewsA: Is it right to prefer composition to inheritance?
TL;DR - Only use inheritance if the subtype can perfectly replace the base type. In addition, reduce the responsibilities of its classes. Use composition to join several isolated responsibilities…