I have a quite inconvenient problem.
Say that I have the following functions
function name(namearg){
...
..
}
function handlefailed(){
..
..
}
function handlecover(){
..
..
}
Now to my problem, I have alot of hard coded html that can't be changed that is calling both functions like this
Link
Link
Link
The problem is the order of which I'm calling the functions, I first want to see which function that is called, either handlefailed() or handlecover(), and then want to know what name that is sent to the name function.
If I would have called the functions in the other way around I would just have done
var theName;
function name(namearg){
theName = namearg
}
function handlefailed(){
callOtherfunctionInAnotherJavascript(getElements(theName + ".failed"));
}
function handlecover(){
callOtherfunctionInAnotherJavascript(getElements(theName + ".cover"));
}
But now this is not possible since I'm calling the name function after the first function.
Is there a way in javascript that "changes" the order of how the functions are evaluated, or do you guys have a clever sollution to my problem, I.E getting the value of the namearg variable and use it in the handlefailed() & handlecover() functions?
var postFix;
function name(namearg){
callOtherfunctionInAnotherJavascript(getElements(namearg + postFix));
}
function handlefailed(){ postFix = '.failed'; }
function handlecover(){ postFix = '.cover'; }
you can empty both functions:
function handlefailed(){
..
..
}
function handlecover(){
..
..
}
and create two new functions that doing what you need
function handlefailed2(){
..
..
}
function handlecover2(){
..
..
}
then call the new functions from inside function name(namearg) according namearg deside to which function you want to call
You can declare another global, handleFunc, and have handlefailed/handlecover assign which one to call in name.
var theName;
var handleFunc = null;
function name(namearg)
{
if(handleFunc instanceof Function)
{
handleFunc(namearg);
handleFunc = null;
}
theName = namearg
}
function handlefailedCallback(namearg){ /* some code */}
function handlefailed()
{
handleFunc = handlefailedCallback;
}
function handlecoverCallback(namearg){ /* some code */}
function handlecover()
{
handleFunc = handlecoverCallback;
}
This gives you the flexibility to continue using name without breaking other areas of the code.
Related
I'm a complete newbie to Javascript so I don't know what its capable of. Any help would be much appreciated!
As the title suggests, I'm trying to pass an argument from a function to name another function inside of it. The method below doesn't work for obvious reasons but I think it conveys what I'm trying to do. The function names need to be very specific for the project I'm working on.
function mainFunc(param1) {
function param1() {}
}
Thanks!
Edit: The software that we are going to start using to go paperless at my work uses a javascript scripting engine. In order for me to do simple things such as:
If at least one of the checkboxes in section A is checked, then you must check at least one checkbox in section B.
I would have to write a function for each and every checkbox field on the form due to the way the software works, the function name has to be specific to the name we assign to the checkbox through their GUI. I was hoping to write a function that writes another function with the specific name, and calls the said function.
function mainFunc(funcName) {
function 'funcName'() {
//do stuff;
}
'funcName'()
}
mainFunc('Checkbox1')
Maybe this will help clarify a little more on what I'm trying to do. Sorry for not being clear the first time around.
You have many options to solve your problem
one option is to return an object with the functions named using the parameters passed to mainFun look at the example below
function mainFunc(param1,param2) {
return {
[param1]:function () {
console.log(" I am function from " + param1)
},
[param2] : function () {
console.log("I am function from " + param2) ;
}
}
}
let hello = 'hello' ;
let greet = 'anything' ;
let functions = mainFunc(hello,greet);
functions['hello']();
functions['anything']();
functions[hello]();
functions[greet]();
if you have many parameters to the mainFun you can also solve it using the arguments object like the example below
function mainFun(par1) {
let myObj = {};
for(let i = 0 ; i<arguments.length;i++){
console.log(arguments[i]);
myObj[arguments[i]] = ()=> {
console.log('You call me from ' + arguments[i]);
}
}
return myObj ;
}
let functions = mainFun('a','b','c','d');
functions['a']();
functions['b']();
functions['c']();
functions['d']();
I've the following script:
gapi.analytics.ready(function() {
viewSelector.on('viewChange', function update (data) {
var title = document.getElementById('view-name');
title.innerHTML = data.property.name + ' (' + data.view.name + ')';
activeUsers.set(data).execute();
renderWeekOverWeekChart(data.ids);
renderTopBrowsersChart(data.ids);
renderTopCountriesChart(data.ids);
setTimeout(function() {
var list = document.getElementsByTagName("tr")[0];
list.getElementsByTagName("th")[0].innerHTML = "Pagina's";
list.getElementsByTagName("th")[1].innerHTML = "Paginaweergaven";
}, 500);
});
});
And within the following code I would like to re-run the update(); function.
function datumwissel( datumbtn ) {
if ( datumbtn.className == 'maand' ) {
datumbtn.className = 'jaar';
dimensions1 = 'ga:month,ga:nthMonth';
start1 = moment(now).date(1).month(0).format('YYYY-MM-DD');
end1 = moment(now).format('YYYY-MM-DD');
start2 = moment(now).subtract(1, 'year').date(1).month(0).format('YYYY-MM-DD');
end2 = moment(now).date(1).month(0).subtract(1, 'day').format('YYYY-MM-DD');
format1 = 'M';
format2 = 'MMM';
update();
}
else {
datumbtn.className = 'maand';
dimensions1 = 'ga:date,ga:nthWeek';
start1 = moment(now).subtract(2, 'day').date(1).format('YYYY-MM-DD');
end1 = moment(now).format('YYYY-MM-DD');
start2 = moment(now).subtract(2, 'day').date(1).subtract(1, 'month').format('YYYY-MM-DD');
end2 = moment(now).subtract(2, 'day').date(1).subtract(1, 'day').format('YYYY-MM-DD');
format1 = 'YYYYMMDD';
format2 = 'Do';
update();
}
}
But somehow this doesn't work. I also tried in the above script:
window.update = function (data) {}. But that also doesn't work.
How can I call the update(); function that is situated inside the gapi.analytics.ready(function() {} ?
Important is that I cannot make it globally as it has to be situated inside the gapi.analytics.ready().
It's really a simple matter of moving the function declaration
function update (data) {
// same as existing code
}
gapi.analytics.ready(function() {
viewSelector.on('viewChange', update );
});
And passing in data needed when you call it in your other function
function datumwissel( datumbtn ) {
if ( datumbtn.className == 'maand' ) {
..........
update(datumbtn);
}.......
Important is that I cannot make it globally as it has to be situated inside the gapi.analytics.ready()
That's not actually true - you can have it global and there at the same time. Whether you want to, is a different manner, as that would pollute the global namespace and so on. However, here is how that can be achieved:
First, extract the update function outside of the ready handler like so
function update (data) {
var title = document.getElementById('view-name');
title.innerHTML = data.property.name + ' (' + data.view.name + ')';
activeUsers.set(data).execute();
renderWeekOverWeekChart(data.ids);
renderTopBrowsersChart(data.ids);
renderTopCountriesChart(data.ids);
setTimeout(function() {
var list = document.getElementsByTagName("tr")[0];
list.getElementsByTagName("th")[0].innerHTML = "Pagina's";
list.getElementsByTagName("th")[1].innerHTML = "Paginaweergaven";
}, 500);
}
This will create a new function with the name update which accepts one parameter called data. Thanks to hoisting it would not matter if it's before or after anywhere you want to use it, as it would be effectively "pulled" to the top.
Next, you can just use the function inside the ready handler like so:
gapi.analytics.ready(function() {
viewSelector.on('viewChange', update);
});
Since .on(events, handler) accepts a function as the second parameter, you can just provide a function reference there. It doesn't matter that your function is technically declared elsewhere, as it is still going to be called with the same arguments. Similarly, if you replace update with alert you will be giving the reference to window.alert so you will get an alert with data.
With that, you can just call the same function in your other piece of code.
That is true for any place that uses callbacks, including setTimeout - you can just give a function reference and it's going to be called. Internally, those kinds of functions almost always do something like callback() or callback(someData), occasionally callback.call(/* parameters */) where callback is the passed in argument. Whether you define that argument as you are calling the function, e.g., selector.on("click", function() {/* code */}) or separately, e.g.,
function clickHandler() { /* code */ }
selector.on("click", clickHandler)
matters little.
With that said, whether you want the function global is a different matter. Unless both pieces of code are in the same place, a global function may be the easiest way. You could, also, namespace anything your app uses, which would partially avoid the global pollution. Not completely, but sometimes you just need to have things living under window if you have multiple files, in which case, you can define your own little corner there to play with: window.myApp = window.myApp || {} would create a new object that can serve as namespace and so you will be able to do things like myApp.update = function(data) { /* code */ } and thus share that code.
If your two pieces of code are indeed in one file, then you merely need to create the function outside both using var update = function(data) { /* code */ } then hand it to each in the exact same way, since update is still going to be a function reference, however, if assigned to a variable, it won't be added to the global namespace (nor would the declaration be hoisted).
I have a simple requirement, I need add the same code to hundreds of other JavaScript functions, the code can be executed at the end of the function, is there a handy way of doing it, like attach an function to another function dynamically, I think yes, because JavaScript is so powerful and too powerful, any ideas?
Note, I need dynamically assign new code or function to existing functions without change existing function's code, please give a solid solution, I can do it in hacky way, but no hacky way please!
The first method that comes to mind is simply create another function:
function primaryFunction() {
// ...
utilityMethod();
}
function otherPrimaryFunction() {
// ...
utilityMethod();
}
function utilityMethod() { ... }
Now utilityMethod() gets called from the end of each other primary function.
There's also a method which requires more code refactoring but is better in the long term: classes/prototypes.
Essentially, you have one "constructor" function which takes a number of parameters for the "class" and returns an class-like object:
function constructor(someClassField, anotherField) {
this.aField = someClassField;
this.fieldTwo = anotherField;
return this;
}
Now if you call this and pass some parameters, you get a class out:
var myClass = new constructor("1", "2");
myClass.aField == "1";
myClass.fieldTwo == "2";
So: If you define your utility method as above, then you can use this: for every primary function you instantiate a new instance of the constructor, with the final code looking like this:
function constructor(primaryFunction) {
this.function = primaryFunction;
this.call = function() {
this.function();
utilityMethod();
}
this.call();
return this;
}
function utilityMethod() { ... }
var primaryMethod = new constructor(function() { ... });
The creation of primaryMethod now automatically calls the primary function followed by the utility method, before returning the object so you can re-call both if you want to.
I see some javascript and try to implement the function seperated to reuse it.
This is the old code:
var ListRenderRenderWrapper = function(itemRenderResult, inCtx, tpl)
{
var iStr = [];
iStr.push('<li>');
iStr.push(itemRenderResult);
iStr.push('</li>');
return iStr.join('');
}
And I would like to make something like this:
function wrapItems(itemRenderResult, inCtx, tpl)
{
var iStr = [];
iStr.push('<li>');
iStr.push(itemRenderResult);
iStr.push('</li>');
return iStr.join('');
}
var ListRenderRenderWrapper = wrapItems(itemRenderResult, inCtx, tpl);
is this ok or do I need to do it in another way?
If you just want to assign that function to a new variable so you can call it with a different name, simply do:
var ListRenderRenderWrapper = wrapItems;
The confusion may be coming from the fact that in JavaScript a function can be stored inside a variable and called as a function later.
This means that:
function thing() { /* code */ }
is the same as:
var thing = function() { /* code */ }
(Aside: I know there are subtle differences with hoisting etc, but for the purposes of this example they are the same).
This might seem like a noob question but I'm not sure what to do. I have function with 2 variables.
function someInfo(myVar1,myVar2)
{
this.lmyVar1=myVar1;
this.myVar2=myVar2;
}
myInstance=new someInfo("string1","string2");
function drawVariables(){
document.write(myInstance.myVar1);
document.write(myInstance.myVar2);
}
I want to use the same drawVariable() for multiple instances. I just can't figure out how the exact syntax for that. How can I make drawVariable() use a different instance of someInfo without repeating anything? Is there a simple example or tutorial I can follow?
Add an argument to the definition of function drawVariables. In the code below, this argument is called info. Now you can use info as your object inside the drawVariables function, and while calling drawVariables function, you can pass whatever instance you want to pass it. drawVariables function would now work with whatever instance you pass it while calling.
function someInfo(myVar1,myVar2)
{
this.myVar1=myVar1;
this.myVar2=myVar2;
}
// Create two separate instances
myInstance=new someInfo("string1", "string1");
myInstance2 = new someInfo("string2", "string2");
// info is the argument that represents the instance passed to this function
function drawVariables(info){
alert(info.myVar1 + ", " + info.myVar2);
}
// Call the function twice with different instances
drawVariables(myInstance);
drawVariables(myInstance2);
See http://jsfiddle.net/WLHuL/ for a demo.
function drawVariables(instance){
document.write(instance.myVar1);
document.write(instance.myVar2);
}
Would it make sense for you to do it this way?
function someInfo(myVar1, myVar2)
{
this.lmyVar1 = myVar1;
this.myVar2 = myVar2;
this.drawVariables = function ()
{
document.write(this.lmyVar1);
document.write(this.myVar2);
}
}
function Test()
{
var obj1 = new someInfo("aaa", "bbb");
var obj2 = new someInfo("xxx", "zzz");
obj1.drawVariables();
obj2.drawVariables();
}