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However, there are important differences that make a map preferable in certain cases. In JavaScript an object is a mapping from property names to values—that is, an associative array with one caveat: the keys of an object must be either a string or a symbol (native objects and primitives implicitly converted to a string keys are allowed).
var x1 = 0; // A global variable, because it is not in any function let x2 = 0; // Also global, this time because it is not in any block function f {var z = 'foxes', r = 'birds'; // 2 local variables m = 'fish'; // global, because it wasn't declared anywhere before function child {var r = 'monkeys'; // This variable is local and does not affect the "birds" r of the parent function. z ...
Though most polyfills target out-of-date browsers, some exist to simply push modern browsers forward a little bit more. Lea Verou's -prefix-free polyfill is such a polyfill, allowing current browsers to recognise the unprefixed versions of several CSS3 properties instead of requiring the developer to write out all the vendor prefixes.
The #ifexist function selects one of two alternatives depending on whether a page exists at the specified title. {{#ifexist: page title | value if page exists | value if page doesn't exist}} The page can be in any namespace, so it can be an article or "content page", an image or other media file, a category, etc.
Previously, JavaScript only supported function scoping using the keyword var, but ECMAScript 2015 added the keywords let and const, allowing JavaScript to support both block scoping and function scoping. JavaScript supports automatic semicolon insertion, meaning that semicolons that normally terminate a statement in C may be omitted in ...
A symbol table may only exist in memory during the translation process, or it may be embedded in the output of the translation, such as in an ABI object file for later use. For example, it might be used during an interactive debugging session, or as a resource for formatting a diagnostic report during or after execution of a program. [2]
jQuery object methods typically also return a jQuery object, which enables the use of method chains: $ ( 'div.test' ) . on ( 'click' , handleTestClick ) . addClass ( 'foo' ); This line finds all div elements with class attribute test , then registers an event handler on each element for the "click" event, then adds the class attribute foo to ...
Comments can explain the author's intent – why the code is as it is. Some contend that describing what the code does is superfluous. The need to explain the what is a sign that it is too complex and should be re-worked.