1.I want to push id[i] into global array.After I pushed then it will be id.length numbers items in each array,but it will be error and says y is not a function.how to solve it?
2.the sendrequest in the bottom will send a xmlhttprequest to server,but I don't understand why it will run first and then the function(parResponse) will be fire after tmpReadRequest.sendReadRequest(); has down.
Thanks a lot
var tes0=new Array();
var tes1=new Array();
var tes2=new Array();
var tes4=new Array();
var tes5=new Array();
function ReadValuePath(id, Variable,id_2) {
var tmpReadCB = function(parResponse)
{
for (var tmpIndex = 0; tmpIndex < parResponse.length; tmpIndex++)
{
var tmpItemValue = parResponse[tmpIndex];//console.log(tmpItemValue);
var tmpValue = (tmpItemValue.mItemValue) ? tmpItemValue.mItemValue : tmpItemValue.mItemResultId;
if(document.getElementById(id[tmpIndex]) != null && document.getElementById(id_2[tmpIndex]).value != 0)
{
document.getElementById(id[tmpIndex]).value = parseFloat(tmpValue).toFixed(2);
}
}
return true;
}
var tmpReadRequest = new OPCReadRequest("DE", tmpReadCB);
for(var z=0;z<5;z++ ){
for(var i = 0; i < id.length; i++)
var y="tes"+z;
y.push(id[i]);
tmpReadRequest.addItem("ab", Variable[i]);
}
}
tmpReadRequest.sendReadRequest();
}
"A variable declared outside a function, becomes GLOBAL.
A global variable has global scope: All scripts and functions on a web page can access it. " # Source
Y is not an array so .push() won't work on it. # Source
To access the global scope through a string literal like you are trying you can use the window object which is the current global scope.
So in your case it would be window[y].push(id[i]);
Another option would be to change you scructure slightly as personally i don't like accessing the window directly.
so you could define your arrays like
var arrays = {
tes0: [],
tes2: [],
tes3: [],
tes4: [],
tes5: [],
}
and access them like:
arrays[y].push(id[i])
EDIT according to comments
So you want to access global variable in a loop. You are half way there. What your doing is building a string y which contains the property name then using that in the square brackets to access that property.
So with the window option that would be:
for(var z=0;z<5;z++ ){
var y="tes"+z;
for(var i = 0; i < id.length; i++)
window[y].push(id[i]);
}
}
or with the second object option
/*
Because arrays is an object we can use Object.keys
This will return an array of the keys in our object which we can loop over to access each one
*/
Object.keys(arrays).forEach(function(key) {
for(var i = 0; i < id.length; i++)
arrays[key].push(id[i]);
}
});
Hope that helps explain
Related
I'm working on an ajax google maps script and I need to create dynamic variable names in a for loop.
for (var i = 0; i < coords.length; ++i) {
var marker+i = "some stuff";
}
What I want to get is: marker0, marker1, marker2 and so on.
and I guess there is something wrong with marker+i
Firebug gives me this: missing ; before statement
Use an array for this.
var markers = [];
for (var i = 0; i < coords.length; ++i) {
markers[i] = "some stuff";
}
I agree it is generally preferable to use an Array for this.
However, this can also be accomplished in JavaScript by simply adding properties to the current scope (the global scope, if top-level code; the function scope, if within a function) by simply using this – which always refers to the current scope.
for (var i = 0; i < coords.length; ++i) {
this["marker"+i] = "some stuff";
}
You can later retrieve the stored values (if you are within the same scope as when they were set):
var foo = this.marker0;
console.log(foo); // "some stuff"
This slightly odd feature of JavaScript is rarely used (with good reason), but in certain situations it can be useful.
Try this
window['marker'+i] = "some stuff";
In regards to iterative variable names, I like making dynamic variables using Template literals. Every Tom, Dick, and Harry uses the array-style, which is fine. Until you're working with arrays and dynamic variables, oh boy! Eye-bleed overload. Since Template literals have limited support right now, eval() is even another option.
v0 = "Variable Naught";
v1 = "Variable One";
for(i = 0; i < 2; i++)
{//console.log(i) equivalent is console.log(`${i}`)
dyV = eval(`v${i}`);
console.log(`v${i}`); /* => v0; v1; */
console.log(dyV); /* => Variable Naught; Variable One; */
}
When I was hacking my way through the APIs I made this little looping snippet to see behavior depending on what was done with the Template literals compared to say, Ruby. I liked Ruby's behavior more; needing to use eval() to get the value is kind of lame when you're used to getting it automatically.
_0 = "My first variable"; //Primitive
_1 = {"key_0":"value_0"}; //Object
_2 = [{"key":"value"}] //Array of Object(s)
for (i = 0; i < 3; i++)
{
console.log(`_${i}`); /* var
* => _0 _1 _2 */
console.log(`"_${i}"`); /* var name in string
* => "_0" "_1" "_2" */
console.log(`_${i}` + `_${i}`); /* concat var with var
* => _0_0 _1_1 _2_2 */
console.log(eval(`_${i}`)); /* eval(var)
* => My first variable
Object {key_0: "value_0"}
[Object] */
}
You can use eval() method to declare dynamic variables. But better to use an Array.
for (var i = 0; i < coords.length; ++i) {
var str ="marker"+ i+" = undefined";
eval(str);
}
In this dynamicVar, I am creating dynamic variable "ele[i]" in which I will put value/elements of "arr" according to index. ele is blank at initial stage, so we will copy the elements of "arr" in array "ele".
function dynamicVar(){
var arr = ['a','b','c'];
var ele = [];
for (var i = 0; i < arr.length; ++i) {
ele[i] = arr[i];
] console.log(ele[i]);
}
}
dynamicVar();
var marker = [];
for ( var i = 0; i < 6; i++) {
marker[i]='Hello'+i;
}
console.log(marker);
alert(marker);
var marker+i = "some stuff";
coudl be interpreted like this:
create a variable named marker (undefined); then add to i; then try to assign a value to to the result of an expression, not possible.
What firebug is saying is this:
var marker; i = 'some stuff';
this is what firebug expects a comma after marker and before i;
var is a statement and don't (apparently) accepts expressions.
Not so good an explanation but i hope it helps.
This looks crazy but it was a much-needed solution for my application to solve the problem of dynamic initialization...
when I inject the services dynamically I would like it to be identified by my own variable which matches the service.
Here is what >I want.
$rootScope.arr = ['MasterLookupService', 'PrinterService'];
for (i = 0; i < arr.length; i++) {
var arr[i] = $injector.get(arr[i]);
}
// it will end up something like this
var MasterLookupService = $injector.get('MasterLookupService');
I tried but none helped
// $rootScope.customObj = {
// MasterLookUpService: $injector.get('MasterLookupService'),
// PrinterService: $injector.get('PrinterService')
// }
I'm not sure about Jquery but this might be what I understand you need.
var arr = ['MasterLookupService', 'PrinterService'];
for(var i =0 ;i < arr.length; i++){
var varname = arr[i];
window[varname] = 'value '+i;
}
alert(MasterLookupService);
window object represents a window containing a DOM document. You may use other object depending upon your environment.
I have the following array and a loop fetching the keys (https://jsfiddle.net/ytm04L53/)
var i;
var feeds = ["test_user_201508_20150826080829.txt:12345","test_user_list20150826:666","test_list_Summary20150826.txt:321"];
for (i = 0; i < feeds.length; i++) {
var feed = feeds[i];
alert(feed.match(/\d+$/));
}
The array will always contain different number of keys, What I would like to do is either use these keys as variables and assign the value after the : semicolon as its value or just create a new set of variables and assign the values found on these keys to them.
How can I achieve this? so that I can then perform some sort of comparison
if (test_user > 5000) {dosomething}
update
Thanks for the answers, how can I also create a set of variables and assign the array values to them? For instance something like the following.
valCount(feeds.split(","));
function valCount(t) {
if(t[0].match(/test_user_.*/))
var testUser = t[0].match(/\d+$/);
}
Obviously there is the possibility that sometimes there will only be 1 key in the array and some times 2 or 3, so t[0] won't always be test_user_
I need to somehow pass the array to a function and perform some sort of matching, if array key starts with test_user_ then grab the value and assign it to a define variable.
Thanks guys for all your help!
You can't (reasonably) create variables with dynamic names at runtime. (It is technically possible.)
Instead, you can create object properties:
var feeds = ["test_user_201508_20150826080829.txt:12345","test_user_list20150826:666","test_list_Summary20150826.txt:321"];
var obj = {};
feeds.forEach(function(entry) {
var parts = entry.split(":"); // Splits the string on the :
obj[parts[0]] = parts[1]; // Creates the property
});
Now, obj["test_user_201508_20150826080829.txt"] has the value "12345".
Live Example:
var feeds = ["test_user_201508_20150826080829.txt:12345","test_user_list20150826:666","test_list_Summary20150826.txt:321"];
var obj = {};
feeds.forEach(function(entry) {
var parts = entry.split(":");
obj[parts[0]] = parts[1];
});
snippet.log(obj["test_user_201508_20150826080829.txt"]);
<!-- Script provides the `snippet` object, see http://meta.stackexchange.com/a/242144/134069 -->
<script src="http://tjcrowder.github.io/simple-snippets-console/snippet.js"></script>
You can do it like this, using the split function:
var i;
var feeds = ["test_user_201508_20150826080829.txt:12345","test_user_list20150826:666","test_list_Summary20150826.txt:321"];
for (i = 0; i < feeds.length; i++) {
var feed = feeds[i];
console.log(feed.split(/[:]/));
}
This outputs:
["test_user_201508_20150826080829.txt", "12345"]
["test_user_list20150826", "666"]
["test_list_Summary20150826.txt", "321"]
Use the split method
var feeds = ["test_user_201508_20150826080829.txt:12345","test_user_list20150826:666","test_list_Summary20150826.txt:321"];
feedMap = {}
for (i = 0; i < feeds.length; i++) {
var temp = feeds[i].split(':');
feedMap[temp[0]] = temp[1];
}
Yields:
{
"test_user_201508_20150826080829.txt":"12345",
"test_user_list20150826":"666",
"test_list_Summary20150826.txt":"321"
}
And can be accessed like:
feedMap["test_user_201508_20150826080829.txt"]
Here is a codepen
it is not very good idea but if you really need to create variables on-the-run here's the code:
for (i = 0; i < feeds.length; i++)
{
var feed = feeds[i];
window[feed.substring(0, feed.indexOf(":"))] = feed.match(/\d+$/);
}
alert(test_user_201508_20150826080829)
Of course you cannot have any variable-name-string containing banned signs (like '.')
Regards,
Michał
I'm trying to learn object oriented javascript and ran into the following problem:
I have an object constructor (is that the right term?) like this:
function itemCreator(itemName, itemType, itemPositionX, itemPositionY) {
this.itemName = itemName;
this.itemType = itemType;
this.itemPositionX = itemPositionX;
this.itemPositionY = itemPositionY;
allItems.push(this); //store all items in a global variable
}//end itemCreator;
//then I use it to create an object
megaRocket = new itemCreator (
'megarocket',
'item_megarocket',
108,
475
)
Now I realised I also need to map these objects to modify different global variables based on which "itemType" the object has. This is where I am stuck. How can I make a global variable that only objects with a specific itemType property can modify?
For example I would like to create an object that increments a variable called amountOfMegarockets, but only if the itemType for that object is "item_megarocket".
I later plan on looping an array of these items to see if player object touches them (to collect the item):
function checkForItems(){
var itemLen =allItems.length;
for (i=0; i < itemLen; i++){
var itemObject = allItems[i];
if ( //checking for "collisions" here
(ship.x < (itemObject.itemBitmap.x + itemObject.size) && (ship.x + shipWidth) > itemObject.itemBitmap.x) &&
(ship.y < (itemObject.itemBitmap.y + itemObject.size) && (ship.y + shipWidth) > itemObject.itemBitmap.y)
){
itemObject.actor.y = -500; //just removing the item from canvas here (temporary solution)
// Here comes pseudo code for the part that I'm stuck with
variableBasedOnItemObject.itemType++;
}
I hope my explanation makes sense to someone!
EDIT:
Bergi's answer makes most sense to me, but I can't get the syntax right. Here's how I'm trying to use Bergi's code:
var amounts = {},
allItems = [];
function itemCreator(itemName, itemType, itemPositionX, itemPositionY) {
this.itemName = itemName;
this.itemType = itemType;
this.itemPositionX = itemPositionX;
this.itemPositionY = itemPositionY;
(amounts[itemType]=2); // this is different from bergi's example because I need to set the initial value of the item to two
//I also shouldn't increase the item amount on creation of the item, but only when it's specifically called from another function
this.increaseCount = amounts[itemType]++; //this should IMO increase the itemType amount inside the amounts object when called, but it doesn't seem to work
}
//creating the object the way bergi suggested:
allItems.push(new itemCreator('shootUp001', 'item_up', 108, 475));
Now here's the problematic part:
function checkForItems(){
var itemLen =allItems.length;
for (i=0; i < itemLen; i++){
var itemObject = allItems[i];
if ( my condition here)
){
//code below is not increasing the value for the current itemType in the amounts object.
//Probably a simple syntax mistake?
itemObject.itemType.increaseCount;
}
}
}
Why is my call of itemObject.itemType.increaseCount; not increasing the value of amounts.itemType?
Increment a global variable called amountOfMegarockets, but only if the itemType for that object is "item_megarocket".
Don't use a global variable for each of those item types. Do use one object (in global or local scope) which counts the amouts of each type on its properties.
var amounts = {},
allItems = [];
function Item(itemName, itemType, itemPositionX, itemPositionY) {
this.itemName = itemName;
this.itemType = itemType;
this.itemPositionX = itemPositionX;
this.itemPositionY = itemPositionY;
amounts[itemType]++ || (amounts[itemType]=1); // count by type
allItems.push(this); // store all items
}
Notice that I wouldn't put all Item instances in an array by default, better omit that line and let it do the caller:
allItems.push(new Item('megarocket', 'item_megarocket', 108, 475));
you can do some things like
(function (global) {
// create a scope
var allItems = [];
global.itemCreator = function(itemName, itemType, itemPositionX, itemPositionY) {
this.itemName = itemName;
this.itemType = itemType;
this.itemPositionX = itemPositionX;
this.itemPositionY = itemPositionY;
allItems.push(this); //store all items in a global variable
}//end itemCreator;
})(this);
this will work. but seriously dont complicate too mutch your code juste to make private var. if someone want to cheat using debugger he will always found a way to do it.
---- edit
If you juste want access to global var base on itemType you can do some thing like:
function checkForItems(){
var itemLen =allItems.length;
for (i=0; i < itemLen; i++){
var itemObject = allItems[i];
if ( //checking for "collisions" here
(ship.x < (itemObject.itemBitmap.x + itemObject.size) && (ship.x + shipWidth) > itemObject.itemBitmap.x) &&
(ship.y < (itemObject.itemBitmap.y + itemObject.size) && (ship.y + shipWidth) > itemObject.itemBitmap.y)
){
itemObject.actor.y = -500; //just removing the item from canvas here (temporary solution)
// Here comes pseudo code for the part that I'm stuck with
if (window[itemObject.itemType + "Data"])) {
variableBasedOnItemObject.itemType++;
} else {
window[itemObject.itemType + "Data"] = {
itemType: 1
}
}
}
}
}
This function seems to be rewriting the value for the 'pages' variable and I'm at my wit's end on this one.
I've tried returning the variable through a function, hardcoding the variable into the function, and a pile of other things, but this seems like it should work.
Any ideas?
EDIT:
The output from should be an array of objects formatted like this {default: "Tax Return", safe: "taxreturn"}. The function, when first called with getPages('Both', 'overview', null) and getPages('Both', null, 'overview') does this, but if you call it more times it will error and you will find that the 'pages' variable is now an array of objects.
var pages = [
"Dashboard",
"Overview",
"Contacts",
"Records",
"Cash Flow",
"Transactions",
"Income",
"Expenses",
"Tax Return"
];
var getPages = function(format, includeOne, excludeOne)
{
var pageStrings = pages;
if(includeOne)
for(var p = 0; p < pageStrings.length; p++)
if(uriSafe(pageStrings[p]) == uriSafe(includeOne))
pageStrings = [pageStrings[p]];
if(excludeOne)
for(var c = 0; c < pageStrings.length; c++)
if(uriSafe(pageStrings[c]) == uriSafe(excludeOne))
pageStrings.splice(c, 1);
var outputArray = [];
switch(format)
{
case 'UriSafe':
for(var i = 0; i < pageStrings.length; i++)
pageStrings[i] = uriSafe(pageStrings[i]);
break;
case 'Both':
for(var x = 0; x < pageStrings.length; x++)
{
pageStrings[x] = {
default: pageStrings[x],
safe: uriSafe(pageStrings[x])
};
}
break;
default:
}
function uriSafe(str)
{
return str.replace(' ', '').toLowerCase();
}
console.log(pageStrings);
return pageStrings;
}
var pageStrings = pages;
is creating a reference to the very same array object. When you access it via pageString, you alter the same object which pages does refer to. To create a copy of it (from which you then can splice, assign properties to, etc without altering pages), use
var pageStrings = pages.slice();
I think your confusion is around the following line
var pageStrings = pages;
This does not create a copy of pages it simply creates a reference to pages. This means any edit you make to the value of pageStrings (clearing, changing elements, etc ...) will show up on pages because they refer to the same variable.
If you want pageStrings to have a copy of the pages array then do the following
var pageStrings = pages.slice(0);
var pageStrings = pages; is your hangup. Keep in mind that when you use = in this way, your new var will be a reference if the argument on the right is and array, object, or function. With strings and numbers you will get the copy you were expecting.