Problems with variable objects in JavaScript

Today I saw a piece of code online, as follows

The code is as follows	Copy Code
CopyText Console.log (typeof (s)); function var s = "1111"; function S () {} Console.log (typeof (s)); Stringconsole.log (typeof (s)); function var s = "1111"; function S () {} Console.log (typeof (s)); String

Pondering for a long time, finally want to understand the problem of JS variable object
The first line outputs a function, because when the scope is entered, the variable object first sweeps through the function of the scope, and then sweeps a variable, then the variable object, and then starts executing the code.

So the first line outputs the function.

and line four because the function is in the variable object before the variable, so in the second line of code s = "1111″, it overwrites the original function variable s, so output string

problem when passing a variable value into an object

The questions are as follows:

The code is as follows	Copy Code
var o = ' left '; var O1 = {drt: ' Left '}; var O2 = [' Left ']; var obj = {o:333}; var obj1 = {o1[drt]:333}; var obj2 = {o2[0]:333};

The first three lines of code are several different ways of declaring a variable, that is, a normal variable, an object, an array, and the last three rows that call each of these 3 variables and insert the object. Here's the problem:
1. Why Obj1 and OBJ2 statements when the direct error?
2. obj did not complain, but why loop his properties when the first attribute is directly called "O" instead of the value "left" of the variable O?

If I want to pass the variable to the object when the attribute, the value of the variable to the object when the property value, only use:

The code is as follows	Copy Code
var O1 = {drt: ' Left '}; var OBJ3={DRT:O1.DRT}

assignment problems of variables in a class

The difference between Object.prop and Object[prop] assignments in JavaScript.

Give a simple example, such as to get the opening price from the stocks information, to form a Openlist object. The implementation code is as follows

The code is as follows

Copy Code

var stocks = { ' 600000 ': {' name ': ' Pu FA Bank ', ' open ': ' 9.67 ', ' new ': ' 9.54 '}, ' 600004 ': {' name ': ' Baiyun airport ', ' open ': ' 6.82 ', ' new ': ' 6.77 '}, ' 600005 ': {' name ': ' Wisco shares ', ' open ': ' 3.23 ', ' new ': ' 3.19 '}, ' 600006 ': {' name ': ' Dongfeng Motor ', ' open ': ' 3.96 ', ' new ': ' 3.86 '} }; var openlist = { ' 600000 ': ' 9.67 ', ' 600004 ': ' 6.82 ', ' 600005 ': ' 3.23 ', ' 600006 ': ' 3.96 ' }; var result = {}; var i; Get the open Price data object For (i in stocks) { Method 1 Result[i] = stocks[i][' open ']; Method 2 RESULT.I = stocks[i][' open ']; }

Here's Method 1, to get the desired result.

But Method 2 Gets the result: {i: "3.96″}."

So the object. Attribute, this attribute cannot be a variable, as I here is an attribute of the object being overwritten.