I am trying to access global variable from function, i want to call variable outside from inside function variable.This is what I tried.
Note: the query function should be work after click on query function from html drop down selection.
Thank you for helping.
HTML
<select name="myInput" id="choice1">
<li><option value="6011">apib_cadastral:bivel</option></li>
<li><option value="6012">apib_cadastral:burhchaura</option></li>
</select>
javascript
var layer_name;
function query() {
var text_value = document.getElementsByName('myInput')[0];
var layer_name = text_value.options[text_value.selectedIndex].text;
}
query();
var config = {
geojson: layer_name,
};
Remove the "var" inside the function. With that you define a new variable that exists inside the function.
You should change your code in this way.
Because, when you re-declare variable inside query() it will occupy another cell from memory with different address. And, variable inside config object cannot access it. It will access layer_name [first defined] which contains undefined value
var layer_name ;
function query() {
var text_value = document.getElementsByName('myInput')[0]
layer_name = text_value.options[text_value.selectedIndex].text;
}
query();
var config = {
geojson: layer_name
}
In addition to other answers, which correctly state that you should remove var from the variable declaration inside the query() function, you could change the function to return the value, rather than relying on shared/global state.
function query() {
var text_value = document.getElementsByName('myInput')[0];
return text_value.options[text_value.selectedIndex].text;
}
var config = {
geojson: query()
};
Note that this may have a performance impact depending on how many times you call query() as the return value would have to be computed each time, but it's worth considering from the perspective of alleviating the need for shared/global state.
Also note, consider replacing var with more modern const and let...
const when the variable is initialised and never needs to change.
let when the variable needs to change beyond initialisation.
function query() {
const text_value = document.getElementsByName('myInput')[0];
return text_value.options[text_value.selectedIndex].text;
}
const config = {
geojson: query()
};
Related
I am trying to save and load the state of some checkbox:
function saveCheckbox () {
var a = document.querySelectorAll('input[type="checkbox"]');
var array = [];
a.forEach(function(checkBox){
array.push({className: checkBox.className, checked: checkBox.checked});
});
localStorage.setItem('Checkboxes', JSON.stringify(array));
console.log(JSON.stringify(array));
}
Seems to save fine, and checking the log as well, but when I try to load it, it doesnt work at all:
function loadCheckbox(){
var a = JSON.parse(localStorage.getItem('Checkboxes'));
a.forEach(function(checkBox){
document.getElementsByClassName(checkBox.className).checked =
checkBox.checked;
});
console.log(JSON.stringify(a));
}
What am I doing wrong here?
Trying declaring a with different varible name and use let in loadCheckbox()
let data = JSON.parse(localStorage.getItem('Checkboxes'));
This can be a typical hoisting related issue. In javascript it takes all the declared variable to the top before runtime. To avoid these you should use let where it uses the block scope of function.
Hello I have created a variable inside the angular.forEach loop that I need outside the loop to bind to the $scope, but i don´t know how to get outside this variable miAlumno.
Thanks.
'use strict';
angular.module('jarciaApp')
.controller('alumnoCtrl', function($routeParams, $firebaseArray) {
var ref = firebase.database().ref('PrimeroA');
var JarciaArray = $firebaseArray(ref);
var id = $routeParams.id;
var curso = $routeParams.curso;
var miAlumno;
JarciaArray.$loaded()
.then(function(miAlumno) {
angular.forEach(JarciaArray, function(alumno, miAlumno) {
if (alumno.Id == id) {
var miAlumno = alumno;
}
})
});
console.log(miAlumno);
});
Don't declare variable miAlumno in loop. Declare it outside and it will be visible.
Pay attention at that console.log(miAlumno), it probably will be always null because of the asynchronous assignement.
If I understand correctly, you are wanting to use the alumno variable you have passed into the function outside the scope of that function?
You can go about it by creating/declaring a global variable outside the function just as you did with miAlumno, then simply assign your global variable to the value your function produces. Also you have miAlumno declared twice, once outside as a global, then inside the for loop.
Apologies if I'm misunderstanding, and if so, please elaborate.
It sounds like you're using the ControllerAs syntax, which means what traditionally would be scope variables are automatically bound as properties of the controller. You can simply set the variable inside of the loop, using a cached value of this:
'use strict';
angular.module('jarciaApp')
.controller('alumnoCtrl', function($routeParams, $firebaseArray) {
var ref = firebase.database().ref('PrimeroA');
var JarciaArray = $firebaseArray(ref);
var id = $routeParams.id;
var curso = $routeParams.curso;
var me = this;
JarciaArray.$loaded()
.then(function() {
angular.forEach(JarciaArray, function(alumno) {
if (alumno.Id == id) {
me.miAlumno = alumno;
}
});
// This will work to show the value
console.log(me.miAlumno);
});
// This still won't work, since $loaded is asynchronous
console.log(this.miAlumno);
});
I've also removed the extra attempts to pass miAlumno to the then function and the callback for forEach; those are unnecessary.
Do note the comments about console.log. I believe the $loaded() is asynchronous; thus it will not be set until whatever process that is actually finishes. If you move the log to inside the then(), you'll see the result.
Iam trying to run an external function inside nightmarejs evalute function...As you can see my code below...
function get_my_links(url){
vo(function* () {
var nightmare = Nightmare();
var href_link = []; // i have tried making it as global without var but did not work
var title = yield nightmare
.goto('https://examply/'+url)
.evaluate(function (href_link,url,get_my_links) {
$('.myclass').each(function() {
href_link.push($(this).attr("href"));
});
if($.isNumeric($("#someid").val()))
{
get_my_links(1)
}
else{
return href_link;
}
},href_link,url);
console.log(title);
yield nightmare.end();
})(function (err, result) {
if (err) return console.log(err);
});
}
get_my_links(0)
By above code I am trying to update href_link ...
1) How to make it Global object,so that everytime the function is called new value should be added with the existing values?
1st The reason
// i have tried making it as global without var but did not work
is not working because though you making the object global but every time you call get_my_links function, it will update the global object to empty array.
For your use case, define href_link before defining get_my_links function. Like
var href_link =[];
function get_my_links() {
...
}
Defining href_link after function definition like ->
function get_my_links() {
...
}
var href_link =[];
will throw an error of undefined value of href_link inside get_my_links function due to hoisting which must be the case you have mentioned in above comment.
electron uses node.js, so you can use the global object of node.js to store the value.
https://nodejs.org/api/globals.html#globals_global
When you use this solution you should be able to access the value also from other parts of your app.
I'm quite new to Angular and am trying to understand how everything works. I've been poking around and couldn't find any information on how to do this. So, I've got a service that defines
this.totalCount = 0;
In my controller, my get request retrieves some emails and then executes a function called addMessage for each message it retrieves. The addMessage function is in my service.
The function in my service looks like this:
this.addMessage = function (messageObj) {
this.messagesList.push(messageObj);
}
Basically, I am trying to increment this.totalCount each time this function is executed so that it will update and then can be displayed in the view. I have it displaying in the view currently, however its number always remains 0.
I've tried the following:
1.
this.addMessage = function (messageObj) {
this.messagesList.push(messageObj);
this.totalCount++;
}
2.
var count = this.totalcount
this.addMessage = function (messageObj) {
this.messagesList.push(messageObj);
count++; //and then attempted to display this value in the view but with no luck
}
Any tips would be greatly appreciated.
try this:
var that = this;
this.addMessage = function (messageObj) {
that.messagesList.push(messageObj);
}
I assume that you're binding the var this way in your controller and your view
Service :
this.totalCount = 0;
this.totalCount++;
Controller :
$scope.totalCount = service.totalCount;
view :
{{totalCount}}
And if you're actually doing it like this, you should face this kind of trouble.
The main problem is that totalCount is a primitive var and doing this.totalCount++ will break the reference. If you want to keep some var you should bind it as a sub-object.
This way :
Service :
this.utils = {};
this.utils.totalCount = 0;
this.utils.totalCount++;
Controller :
//This is the most important part. You bind an object. Then even if you loose the totalCount reference, your object will keep its own reference.
$scope.myServiceUtils = service.utils;
View :
{{myServiceUtils.totalCount}}
Actually in service (it's a matter of taste) i prefer a lot to use the object syntax instead of this (as "this" can be confusing)
This way :
var service = {};
service.utils.totalCount = 0;
service.addItem = function(){
...
}
return service;
Hope that was your issue.
You pass argument to another function which has different scope than your service. It is trick with assigning current object to variable, which is visible from function.
var that = this;
this.addMessage = function (messageObj) {
that.messagesList.push(messageObj);
that.totalCount++;
}
Should work.
So you assign that variable with current object, which is visible in inner function scope.
In a function addMessage body, this refers to function scope which is new, and there is no compiler error, but messagesList is a null object and totalCount is incremented, but after program leave function, it's not visible in service, because it is in a function scope which isn't assigned to any variable.
To update service variable as it changes in your controller, use $watch.
$scope.$watch(function() {
return messagesService.totalCount;
}, function(new,old){
$scope.totalmessagecount = messagesService.totalCount;
});
First parameter of $watch if function which return observed for change element. Another is standard function to perform operation after update.
I have a function that create and store an array for all the p elements:
function dummyArray(){
var $dummy= $('p');
var dummy= [];
i = 0;
$dummy.each(function()
{
dummy[i++] =$(this).html();
});
return dummy;
}
Now, in order to reuse the array in another function, I can use dummyArray() and dummyArray()[0] to access the individual data.
function initAll(){
//dummyArray();
//dummyArray()[0];
}
However I want to store it inside a variable like below but it gives me error.
function initAll(){
var allArray = dummyArray();//error
}
Is there a way to store it inside a variable or is there a better way of doing this?
After cleaning up my code I noticed that using var allArray = dummyArray(); does work, the error was generated from something else. cheers~
Edited:
The error I found out was the function name cannot be the same as the new variable name declared even though the () aren't there.
var dummyArray = dummyArray();//error
var allArray = dummyArray();//works