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Javascript Articles
Page 528 of 534
When should I use a semicolon after curly braces in JavaScript?
In JavaScript, Semicolons are optional. Simple statements in JavaScript are generally followed by a semicolon character, just as they are in C, C++, and Java. JavaScript, however, allows you to omit this semicolon if each of your statements is placed on a separate line. It is a good programming practice to use semicolons.In JavaScript, use a semi-colon after a statement. Let’s see an example of a variable assignment:var s = function() { alert("Hello World!"); };However, semicolons aren’t necessary for the following function declarations:function() { alert("Hello World!"); };
Read MoreWhat is the difference between Bower and npm in JavaScript?
npmnpm is generally used for managing Node.js modules and does nested dependency tree. It also works for front-end and used for developer tools like Grunt, CoffeeScript, etc.Without using nested dependencies it is difficult to avoid dependency conflicts. So, using npm has proven to be great.Whatever you add in Node is structured as modules. On using NPM for browser-side dependencies, you'll structure your code like Node.Here’s the dependency structure:project root [node_modules] -> dependency P -> dependency Q [node_modules] -> dependency P -> dependency R [node_modules] -> dependency Q [node_modules] -> dependency P -> dependency SBower Bower requires a flat dependency tree and ...
Read MoreWhich one is the Python module to obfuscate javascript?
You can use the jsmin module to minimize/obfuscate javascript code using Python. Install jsmin using:$ pip install jsminTo use jsmin in your python project to minimize a js file, say hello.js, you can use it as follows:>>> from jsmin import jsmin >>> with open('hello.js') as js_file: ... minified = jsmin(js_file.read()) >>> print minifiedYou'll get the minified JS code printed to your shell. You can also use jsmin as a command line tool:$ python -m jsmin hello.jsYou can read more about jsmin on pypi docs: https://pypi.python.org/pypi/jsmin
Read MoreHow to check if a string has a certain piece of text in JavaScript?
The jQuery search() method is used to check whether a string contains a certain text in JavaScript.You can try to run the following code to check whether “Tutorialspoint: Free Video Tutorials” contains the “Free Video” text in JavaScript or not: JavaScript String search() Method var re = "Free Video"; var str = "Tutorialspoint: Free Video Tutorials"; if ( str.search(re) == -1 ) { document.write("Does not contain" ); } else { document.write("Contains" ); }
Read MoreWorking with forms in React.js
In simple html form, the form elements keeps value with it internally and submit on form submission button.Example Form Example User Name: In above example, we have a simple input called username and we can receive its value on form submission. The default behavior of html form is to navigate to new page i.e. the post form submission page.But it can give more advantage if we have a form submission handler JavaScript function which can validate the form data as ...
Read MoreJavaScript's Boolean function?
Boolean functionWhile developing, a developer may come across yes/no situation. At that point of time Boolean() function can be used. It results only in true or false. Let's discuss it in detail.syntaxBoolean(exp);It takes an expression and scrutinizes it and displays either true or false based on the validity of the expression.Example-1In the following example, various values have been checked whether they are true or not using Boolean() function. If any value has any legitimate value then it results in true else it results in false. var a = 0; ...
Read MoreFirst element and last element in a JavaScript array?
An array is a group of elements. Each element has its own index value. We can access any element using these indexes. But in the case of the last element, we don't know the index until we know the number of elements present in the array. In this case, we have to use logic. Let's discuss these details in a nutshell.Accessing the first elementSince we know the index of the first element we can get the value of that element very easily. Let the array be arr. then the value of the first element is arr[0].ExampleIn the following example, there are ...
Read MoreValue of the class attribute node of an element in JavaScript?
Javascript has provided the getAttributeNode() method to find the attribute node with the specified name of an element, as an attribute object. If the attribute does not exist, the return value is null or an empty string ("").syntaxelement.getAttributeNode(attributename);It returns the attribute object representing the specified attribute node ExampleIn the following example, there are two heading tags with different classes. Those tags when accessed by the getAttributeNode() can return the attribute class with which they attached. It works the same as an array. We can access the multiple classes only by providing their index numbers. Tutorix Tutorialspoint var elmnt = document.getElementsByTagName("h2")[1]; var value = elmnt.getAttributeNode("class").value; document.getElementById("attribute").innerHTML = value; OutputTutorix ...
Read MoreHow to insert an 8-byte integer into MongoDB through JavaScript shell?
You can use below syntax for inserting an 8-byte integer in MongoDB through JavaScript shell −anyVariableName= {"yourFieldName" : new NumberLong("yourValue")};To display the above variable, you can use the variable name or printjson(). Following is the query to insert 8 byte integer in MongoDB −> userDetail = {"userId" : new NumberLong("98686869")}; { "userId" : NumberLong(98686869) }Let us display the above variable value using variable name. The query is as follows −> userDetailThis will produce the following output −{ "userId" : NumberLong(98686869) }Let us display the variable value using printjson() −> printjson(userDetail); This will produce the following output −{ "userId" : NumberLong(98686869) }
Read MoreExplain in detail about the memory life cycle of JavaScript?
Memory cycleRegardless of the programming language, the memory cycle is almost same for any programming language. There are 3 steps in a memory life cycle1) Allocation of memory .2) use the allocated memory(reading or writing)3) Release the allocated memory when it is unnecessary.The first and last parts are directly connected in low-level languages but are indirectly connected in high-level languages such as JavaScript.1) Allocation of memory in javascriptJavaScript is called garbage collected language, that is when variables are declared, it will automatically allocate memory to them.When there are no more references for the declared variables, allocated memory will be released. ExampleIn the ...
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