JavaScript arrays are simply a specialized kind of object. Therefore, the for/in loop enumerates array
indexes as well as object properties.
The for/in loop does not specify the order in which the properties of an object are assigned to the
variable. There is no way to tell what the order will be in advance, and the behavior may differ among
implementations or versions of JavaScript. If the body of a for/in loop deletes a property that has not yet
been enumerated, that property will not be enumerated. If the body of the loop defines new properties,
whether or not those properties will be enumerated by the loop is implementation-dependent.
The for/in loop does not actually loop through all possible properties of all objects. In the same way that
some object properties are flagged to be read-only or permanent (nondeletable), certain properties are
flagged to be nonenumerable. These properties are not enumerated by the for/in loop. While all userdefined
properties are enumerated, many built-in properties, including all built-in methods, are not
enumerated.
indexes as well as object properties.
The for/in loop does not specify the order in which the properties of an object are assigned to the
variable. There is no way to tell what the order will be in advance, and the behavior may differ among
implementations or versions of JavaScript. If the body of a for/in loop deletes a property that has not yet
been enumerated, that property will not be enumerated. If the body of the loop defines new properties,
whether or not those properties will be enumerated by the loop is implementation-dependent.
The for/in loop does not actually loop through all possible properties of all objects. In the same way that
some object properties are flagged to be read-only or permanent (nondeletable), certain properties are
flagged to be nonenumerable. These properties are not enumerated by the for/in loop. While all userdefined
properties are enumerated, many built-in properties, including all built-in methods, are not
enumerated.
分享到：
发表评论
-
Extending Built-in Types
2009-01-08 13:55 728The Function.apply( ) method is ... -
Breakpoints using closures
2009-01-07 13:43 870// // This function implements ... -
Private properties with closures
2009-01-07 13:13 768// // This function adds proper ... -
Constructor Functions
2009-01-07 00:42 763the new operator creates a new ... -
Functions as Methods
2009-01-07 00:39 809When a function is invoked as a ... -
The callee Property
2009-01-07 00:02 667In addition to its array elemen ... -
Variable-Length Argument Lists: The Arguments Obje
2009-01-06 23:06 794The Arguments object has one ve ... -
Function Literals
2009-01-06 21:50 705Although function literals crea ... -
Nested Functions
2009-01-06 21:09 770Nested functions may be defined ... -
Deleting Array Elements
2009-01-05 22:11 572The delete operator sets an arr ... -
Reading and Writing Array Elements
2009-01-05 22:00 771Note that array indexes must be ... -
The valueOf() Method
2009-01-05 18:05 748... -
The toLocaleString() Method
2009-01-05 18:02 858In ECMAScript v3 and JavaScript ... -
The constructor Property
2009-01-05 17:51 794[size=medium]Since constructor ... -
the empty statement
2009-01-05 00:29 788[size=medium]When you intention ... -
with
2009-01-05 00:27 686[size=medium]The with statement ... -
try/catch/finnaly
2009-01-05 00:17 892If control leaves the try bloc ... -
throw
2009-01-04 23:56 694The tHRow statement has the fol ... -
return
2009-01-04 23:52 818If a function executes a return ... -
functions
2009-01-04 23:48 799[size=medium]Technically speaki ...
相关推荐
Oracle用三种循环方法输出乘法表，比如loop的用法： m := 1; loop n := 1; loop dbms_output.put(m||'*'||n||'='||m*n||' '); n := n + 1; exit when n > m; end loop; dbms_output.put_line(''); ...
Human-in-the-Loop Machine Learning lays out methods for humans and machines to work together effectively. Summary Most machine learning systems that are deployed in the world today learn from human ...
在Oracle SQL中，有多种方法来操作游标，包括使用`FOR..LOOP`结构和传统的`OPEN..FETCH..CLOSE`语法。这篇文章将对比这两种方式，探讨它们的优缺点以及在不同场景下的适用性。 首先，`FOR..LOOP`结构是Oracle提供的...
### Hardware-in-the-loop (HIL) Simulation for CPU-GPU Heterogeneous Platforms #### 摘要与背景 在嵌入式系统中，多核CPU/GPU异构平台变得越来越流行。为了观察整个软件堆栈在系统模拟模型上的内部行为而无需...
避免使用`for in`循环遍历数组，采用经典`for`循环并缓存`length`，明确理解`Array`构造函数的行为，以及正确使用`typeof`和`instanceOf`进行类型检查，这些都是编写高质量JavaScript代码的关键。
FOR x IN REVERSE 1..10 LOOP DBMS_OUTPUT.PUT_LINE('内:x='||x); END LOOP; DBMS_OUTPUT.PUT_LINE('end loop:x='||x); END; ``` While 循环 While循环是一种条件循环语句，用于重复执行某些语句。其基本语法...
人在环路是通过整合人类的知识和经验，以最小的代价训练出准确的预测模型。人与机器更密切地进行合作、让双方发挥各自最主要的优势，达到效益最大化。来自华东师范大学研究人员关于人在环路机器学习综述论文，详细...
FOR n IN 100..200 LOOP flag := TRUE; FOR i IN 2..n - 1 LOOP IF MOD(n, i) = 0 THEN flag := FALSE; END IF; END LOOP; IF (flag = TRUE) THEN DBMS_OUTPUT.PUT_LINE(n); END IF; END LOOP; END; ``` ...
for i in 1..9 loop for j in 1..i loop Dbms_Output.put(i || '*' || j || '=' || i*j); dbms_output.put(' '); end loop; dbms_output.new_line; end loop; end; ``` 2. **WHILE循环**： WHILE循环基于...
在Costas环路的仿真中，`for loop`可能用于模拟不同初始条件下的系统响应，或者测试不同参数设置对系统性能的影响。 5. **Simulink仿真步骤** - 设置输入信号：模拟接收到的调制信号。 - 构建Costas环路模型：...
Loop-in-Loop优化方法是一种针对MATLAB编程环境中的并行计算技术，主要目的是提升多层循环（特别是For或Parfor循环）的执行效率。在MATLAB中，循环通常是计算密集型任务，尤其是在处理大型数据集时，循环的执行速度...
CGRAs for acceleration, and the mapping of loops onto CGRA is quite a challenging work due to the parallel execution paradigm and constrained hardware resource. To map loops onto CGRAs efficiently, it...
FOR IN循环的基本形式是将一个列表或一系列值与`IN`关键字配对，以迭代列表中的每个元素。例如： ``` :FOR ${n} IN 1 2 3 \ Log ${n} ``` 在这个例子中，循环会运行三次，每次将`${n}`分别赋值为1、2和3。如果...
This document describes the Indy RF Power Control Loop and Calibration for the Indy R1000/R2000 platform.
### Hardware-in-the-loop (HIL) Simulation for CPU-GPU Heterogeneous Platforms #### 背景与概述 在现代计算领域，随着SoC（System-on-a-Chip）技术的发展，越来越多的高性能计算任务需要在CPU-GPU这样的异构...
Loop control is an essential area of electronics engineering that today's professionals need to master. A control system is a complex electronics architecture involving setpoints and targets. One ...
学校子域（即“ lynbrook”，“ montavista”等），用户名，密码，每个班级的总成绩百分比（用于通知）以及主题选择/定制选项源代码和更多详细信息，请访问https://github.com/maheshmurag/InTheLoop功能：...
请通过发送电子邮件至maheshmmurag@gmail.com或在https://github.com/maheshmurag/InTheLoop/issues上发布报告您遇到的任何问题-该扩展程序不会尝试处理异常格式并可能计算出不正确的结果，而是自动禁用了成绩计算...
// - Functional objects for use in STL algorithms // // From this template, we intstantiate two classes: CStdStringA and // CStdStringW. The name "CStdString" is just a #define of one of these, //...