我无法访问在循环内创建的对象..
// global var $subtypes //
...
... code ...
...
$subtypes = {};
for ( var $cols = 0; $cols < $subtypecols.length; $cols++ ) // Here i can got from 1 to 20
{
var columnName = 'column' + $cols; // column0, column1, column2 ... column20
$subtypes.columnName = { }; // creating empty object
for ( var $rows = 0; $rows < $subtypeTableRows.length; $rows++ ) // from 1 to 10.
{
var rowNumber = 'row' + $rows; // row1, row2, row3 ... row7
$subtypes.columnName.rowNumber = { 'count' : -1, 'price' : -1 };
};
};
//console.log ( 'l ' + $subtypes['column3']['row5'] ); //undefined is not an object (evaluating '$subtypes['column3']['row5']')
//console.log ( 'l ' + $subtypes['column3']['row5'].count ); //undefined is not an object (evaluating '$subtypes['column3']['row5']')
//console.log ( 'l ' + $subtypes[column3][row5].count ); //ReferenceError: Can't find variable: column3
//console.log ( 'l ' + $subtypes[column3][row5] ); //ReferenceError: Can't find variable: column3
//console.log ( 'l ' + $subtypes.column3.row5 ); //expected 'object', got: undefined is not an object (evaluating '$subtypes.column4.row2')
我做错了什么?
UPD 1:该代码不起作用..
for (var o = 0; o < 5; o++)
{
var $prevNum = 'prev' + o;
var $prevTxt = $nodelist[o].textContent
$itemConfig = { $itemWithPreviews : { $prevNum : $prevTxt } };
// i got string name '$prevNum' : and value from valiable $prevTxt.
$itemConfig = { $itemWithPreviews : { [$prevNum] : $prevTxt } };
// JS script can't start
};
更新2:
var $root = {};
var $root[0] = {}; // data
var $root[1] = {}; // another data
var $root[2] = {}; // here will be stored buttons and rows..
for ( var $buttons = 0; $buttons < 10; $buttons++ ) // 10 buttons
{
var buttonName = 'button' + $buttons; // button0, button1, button2 ... buttom9
var objButton = { };
objButton[buttonName] = { };
$root[2].push( objButton ); //here all's ok: { "button0":{} }, { "button1":{} } ...
for ( var $row = 0; $row < 5; $row++ )
{
var rowNumber = 'row' + $row; // row0, row2 ... row4
var objRow = { };
objRow[rowNumber] = { };
$root[2][buttonName].push ( objRow );
// Expect.: { "button0": { "row0": { }, "row1": { }, "row2": { }, ... } }, { "button1": { "row0": { }, "row1": { }, "row2": { }, ... } } ...
// Got: ERROR: TypeError: undefined is not an object (evaluating '$root[2][buttonName].push')
//same situation...
$root[2][$buttons].push ( objRow );
// Got: ERROR: TypeError: undefined is not a function (evaluating '$root[2][$buttons].push ( objRow )')
};
};
最佳答案
你做了:
$subtypes.columnName = { };
$subtypes.columnName.rowNumber = { 'count' : -1, 'price' : -1 };
它创建了对象:
$subtypes["columnName"]["rowNumber"];
如果你想创建$subtypes['column3']['row5']
那么你需要这样做:
$subtypes[columnName] = { };
$subtypes[columnName][rowNumber] = { 'count' : -1, 'price' : -1 };
请记住,点符号 a.b.c
相当于 a['b']['c']
。因此,您的 console.log()
也可以写为:
console.log ( 'l ' + $subtypes.column3.row5 );
更新:
至于你的后续问题,当你这样做时
$itemConfig = {$itemWithPreviews : { $prevNum : $prevTxt }};
您正在创建以下对象:
$itemConfig["$itemWithPreviews"]["$prevNum"] = $prevTxt;
属性名称不是变量。它们始终被解释为文字字符串。因此 $prevNum
是 "$prevNum"
而不是 "prev0"
等。另一方面,属性值是变量,因此 $prevTxt
将具有相同的值。
ES6(也称为 ES2015)引入了新语法 called computed property names这可以让你做你想做的事。执行此操作的语法使用熟悉的方括号:
$itemConfig = {[$itemWithPreviews] : {[$prevNum] : $prevTxt }};
但是,截至 2017 年 1 月,只有 Chrome、Firefox 和 Node.js 支持此语法。这在其他浏览器中不起作用,因此您必须采用老式方式:
$itemConfig = {};
$itemConfig[$itemWithPreviews] = {};
$itemConfig[$itemWithPreviews][$prevNum] = $prevTxt;
如果您想在循环中执行此操作,可以有条件地初始化属性:
$itemConfig = {};
for (var o = 0; o < 5; o++) {
var $prevNum = 'prev' + o;
var $prevTxt = $nodelist[o].textContent;
if ($itemConfig[$itemWithPreviews] === undefined) {
$itemConfig[$itemWithPreviews] = {};
}
if ($itemConfig[$itemWithPreviews][$prevNum] === undefined) {
$itemConfig[$itemWithPreviews][$prevNum] = {};
}
$itemConfig[$itemWithPreviews][$prevNum] = $prevTxt;
}
关于javascript - 访问动态创建的对象..js,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/41464578/