I want to pass a local variable from one function to another and I have tried some solutions but they didn't work because I have a click function, I need to put the variable first of all and I don't how to do it, also I declared the variable outside the function but if I use it outside of all the functions it doesn't has all its values or inside the function resaltar nothing appears, any help is welcome
let children=$('div[class^="fila"], div[class^="pieceRow"]' ).children()
var clase
$(children).each(function getClass(){
clase=$(this).attr('class')
$(clase).on('click', function resaltar(){
if (clase==clase) {
$(this).addClass('shadow')
}
})
})
this is the html code https://jsfiddle.net/qb5fwcus/
Please try this code :
let children = $('div[class^="fila"], div[class^="pieceRow"]' ).children();
$(children).on('click', function(){
var clase = $(this).attr('class');
resaltar(clase);
})
function resaltar(clase){
$('.shadow').removeClass('shadow');
$('.' + clase).addClass('shadow');
}
Explanation : You can not pass any value for the callback function for any event handler. Either it can be an anonymous function, or a function, not requiring any argument. However, you can achieve that, by making the callback function anonymous, and call any function from it. In this way, you can pass variables.
PS : Let me know if I got it wrong in any manner :)
Let's assume that you will be passing it to a pure JS function.
function myFunc() {
console.log("My function!");
}
In your 'click', you're calling the function ''resalter'', that you're also defining on the spot.
You want to call myFunc, so:
$(clase).on('click', myFunc())
Now, myFunc is not expecting a variable. Let's just pass a variable:
function myFunc(myVar) {
console.log("Passing a variable of type: " + typeof myVar);
}
Now, you're only expected to pass this var in the function you're calling. Given the previous example I gave, we have:
let x = 1; // our variable
$(clase).on('click', myFunc(x))
This way you're passing 'x' as a variable, of type integer. Use this code as inspiration to try and reach your goal. It is a bit hard to give a more exact answer, given that we don't know what variables have to be passed to what function and what the purpose is.
Good luck!
Related
I am trying to find out the difference between 2 functions. In my
react native app I use an AppState eventlistener to check if the app
is running in the background or foreground (see code below):
AppState.addEventListener('change', this._handleAppStateChange);
the function looks like this:
_handleAppStateChange = (nextAppState) => {
console.log('nextAppState', nextAppState)
this.setState({
appState: nextAppState
});
};
I did not like the way te function is made because in the listener you call it without a parameter
but it the function itself it has a parameter. So I wanted to change this to make it more clear.
This is what is made:
_handleAppStateChange (nextAppState) {
console.log('nextAppState', nextAppState)
this.setState({
appState: nextAppState
});
};
This works fine the nextAppState is still logged but the setstate does not work anymore
is says that it`s not a function. Can someone explain me why?
And can someone explain me which of both functions is the best to use.
Thx a lot!
Start using arrow functions, one of the reason why arrow functions were created is for the problem you have mentioned i.e losing this in the function context.
So in order for your function to work you need to bind the function to this.
In your constructor add this line
this._handleAppStateChange = this._handleAppStateChange.bind(this)
Or you can replace this function
AppState.addEventListener('change', this._handleAppStateChange);
to
AppState.addEventListener('change', (nextAppState) => this._handleAppStateChange(nextAppState));
Bonus.
If you need to pass extra parameter other than nextAppState or which is in state. This line wont work
AppState.addEventListener('change', (nextAppState, this.state.someRandmValue) => this._handleAppStateChange(nextAppState, this.state.someRandmValue));
As this.state.someRandomValue is undefined since handleAppState wont emit this value instead use this
AppState.addEventListener('change', (nextAppState) => this._handleAppStateChange(nextAppState, this.state.someRandmValue));
Basically when running addEventListener I cannot access any of my saved variables from outside the function I am creating.
In the following code I always get the error Property 'xAxisLabel' does not exist on type 'HTMLElement'.
xAxisLabel:string = 'xAxis';
xAxisField:HTMLElement;
filterChanged(element: HTMLElement) {
element.addEventListener("change", function(){
this.xAxisLabel = 'Countries';
});
}
ngOnInit() {
this.xAxisField=document.getElementById('xAxisField');
this.filterChanged(this.xAxisField);
}
I am sure it's a fairly simple solution but I haven't been able to find it online. Any help would be appreciated.
It is due to 'this' keyword binding. You need to change your code to use arrow function, so:
filterChanged(element: HTMLElement) {
element.addEventListener("change", () => {
this.xAxisLabel = 'Countries';
});
}
now this.xAxisLabel refers to correct value
I'm trying to use a script to replace a particular string with a different string. I think the code is right, but I keep getting the error "Object does not allow properties to be added or changed."
Does anyone know what could be going wrong?
function searchAndReplace() {
var teams = SitesApp.getPageByUrl("https://sites.google.com/a/directory/teams");
var list = teams.getChildren();
list.forEach(function(element){
page = element.getChildren();
});
page.forEach(function(element) {
var html = element.getHtmlContent();
html.replace(/foo/, 'bar');
element.setHtmlContent = html;
});
};
Try This:
Javascript reference:
The replace() method returns a new string with some or all matches of a pattern replaced by a replacement.
I think the issue here is that forEach cannot change the array that it is called upon. From developer.mozilla.org "forEach() does not mutate the array on which it is called (although callback, if invoked, may do so)."
Try doing it with a regular loop.
I was wondering if it was possible to pass a function foo() as an attribute func="foo()" and have it called this.func() inside of the polymer element?
<foo-bar func="foo()"></foo-bar>
Polymer({
is: 'foo-bar',
properties: {
func: Object,
},
ready: function() {
this.func();
}
});
I've been trying to get this working for ages with no luck.
Thanks in advance.
<foo-bar func="foo()"></foo-bar>
Polymer({
is: 'foo-bar',
properties: {
func: {
type: String, // the function call is passed in as a string
notify: true
},
attached: function() {
if (this.func) {
this.callFunc = new Function('return '+ this.func);
this.callFunc(); // can now be called here or elsewhere in the Polymer object
}
});
So the trick is that "foo( )" is a string when you first pass it to the Polymer element. I fought with this for a while as well and this is the only way I could find to get it done. This solution creates a function that returns your function call, which you assign as the value of one of your polymer element properties.
Some people might say you shouldn't use the Function constructor because it is similar to eval( ) and.... well you know, the whole 'eval is evil' thing. But if you're just using it to return a call to another function and you understand the scope implications then I think this could be an appropriate use-case. If I'm wrong I'm sure someone will let us know!
Here's a link to a nice SO answer about the differences between eval( ) and the Function constructor in case it can help: https://stackoverflow.com/a/4599946/2629361
Lastly, I put this in the 'attached' lifecycle event to be on the safe side because it occurs later than 'ready'. I'm not sure if an earlier lifecycle event or 'ready' could be used instead of 'attached'. Perhaps someone can improve this answer and let us know.
I wrote code below that is working perfectly for displaying the results of my sales tax calculation into a span tag. But, I am not understanding how to change the "total" value into a variable that I can work with.
<script type="text/javascript">
function doStateTax(){
var grandtotalX = $('#GRANDtotalprice').val();
var statetaxX = $('#ddl').val();
$.post('statetax.php',
{statetaxX:statetaxX, grandtotalX:grandtotalX},
function(data) {
data = $.parseJSON(data);
$('.products-placeholder').html(data.products);
$('.statetax-placeholder').html(data.statetax);
$('.total-placeholder').html(data.total);
// ...
});
return false;
};
</script>
Currently, $('.total-placeholder').html(data.total); is successfully placing the total number into here:
<span class="total-placeholder"></span>
but how would I make the (data.total) part become a variable? With help figuring this out, I can pass that variable into a hidden input field as a "value" and successfully give a proper total to Authorize.net
I tried this and id didn't work (see the testtotal part to see what I'm trying to accomplish)..
function(data) {
data = $.parseJSON(data);
$('.products-placeholder').html(data.products);
$('.statetax-placeholder').html(data.statetax);
$('.total-placeholder').html(data.total);
$testtotal = (data.total);
// ...
If you are using a hidden field inside a form, you could do:
//inside $.post -> success handler.
$('.total-placeholder').html(data.total);
$('input[name=yourHiddenFieldName]', yourForm).val(data.total);
This will now be submitted along with the usual submit. Or if you want to access the data elsewhere:
var dataValue = $('input[name=yourHiddenFieldName]', yourForm).val();
The "data" object you are calling can be used anywhere within the scope after you have a success call. Like this:
$.post('statetax.php',
{statetaxX:statetaxX, grandtotalX:grandtotalX},
function(data) {
data = $.parseJSON(data);
var total = data.total;
var tax = data.total * 0.19;
});
return false;
};
Whenever you get an object back always try to see with an alert() or console.log() what it is.
alert(data); // This would return <object> or <undefined> or <a_value> etc.
After that try to delve deeper (when not "undefined").
alert(data.total); // <a_value>?
If you want 'testotal' to be recognized outside the function scope, you need to define it outside the function, and then you can use it somewhere else:
var $testtotal;
function(data) {
data = $.parseJSON(data);
$('.products-placeholder').html(data.products);
$('.statetax-placeholder').html(data.statetax);
$('.total-placeholder').html(data.total);
$testtotal = (data.total);
EDIT:
The comments are becoming too long so i'll try and explain here:
variables defined in javascript cannot be accessed by PHP and vice versa, the only way PHP would know about your javascript variable is if you pass it that variable in an HTTP request (regular or ajax).
So if you want to pass the $testtotal variable to php you need to make an ajax request(or plain old HTTP request) and send the variable to the php script and then use $_GET/$_POST to retrieve it.
Hope that answers your question, if not then please edit your question so it'll be clearer.