In the code presented above, this variable is len (one common name for such a variable). Declaring multiple variables in the loop's header Notice one subtle but important thing in the code above. In addition to the first variable i, another variable len is declared in the loop's header....
function goLoop(){ for (var i = 0; i < 10; i++) { console.log(i); //output = numbers between 0 and 9 } } goLoop(); console.log(i) //returns error Listing 3-6When Creating a Variable Using the var Keyword Inside a Function, the Execution Context is Local to the Function ...
ForStmt: a “for” statement; use ForStmt.getInit() and ForStmt.getUpdate() to access the init and update expressions, respectively. EnhancedForLoop: a “for-in” or “for-of” loop; use EnhancedForLoop.getIterator() to access the loop iterator (which may be a expression or variable ...
In most other languages, the code above would lead to an error because the “life” (i.e., scope) of the variableiwould be restricted to theforblock. In JavaScript, though, this is not the case, and the variableiremains in scope even after theforloop has completed, retaining its last...
For loopLooping an ArrayLooping through HTML headersWhile loopDo While loopBreak a loopBreak and continue a loopUse a for...in statement to loop through the elements of an object JavaScript Error Handling The try...catch statementThe try...catch statement with a confirm boxThe onerror event...
Ryan Dahl 2009 开发的 Node.js (介绍参看作者jsconf演讲)就是用 CommonJS 的模块加载器。Node.js 链接了 POSIX API,网络和文件操作,有个自己的 Event Loop,有些基础的 C 模块,还包含了 V8 引擎。 2010 年开始出现其他语言源码转 js 源码这种转译器的风潮,最有代表的是 CoffeeScript,CoffeeScript 某种程度...
toplevel (default: false)— set to true if you wish to enable top level variable and function name mangling and to drop unused variables and functions. v8 (default: false)— enable workarounds for Chrome & Node.js bugs. warnings (default: false)— pass true to return compressor warnings ...
5.3 Use object destructuring for multiple return values, not array destructuring. Why? You can add new properties over time or change the order of things without breaking call sites. // bad function processInput(input) { // then a miracle occurs return [left, right, top, bottom]; } // ...
First we initialize the variables sum (for calculating the sum) and counter (for counting first 100 numbers). As opposed to the for loop, in a while loop we have to manually increment the counter inside the loop code. If you forget to do that, then the counter will always be less ...
Note that thevarstatement can also appear as part of theforandfor/inloops (introduced inChapter 6), allowing you to succinctly declare the loop variable as part of the loop syntax itself. For example: for(var i = 0; i < 10; i++) document.write(i, ">br<"); for(var i = 0, ...