I am having trouble passing a kata. I believe I am on the right track, but do not fully understand how to retrieve the desired results.
The Instructions
Write a method that takes in a function and the arguments to the function and returns another function which when invoked, returns the result of the original function invoked with the supplied arguments.
Example Given
Given a function add
function add (a, b) {
return a + b;
}
One could make it lazy as:
var lazy_value = make_lazy(add, 2, 3);
The expression does not get evaluated at the moment, but only when you invoke lazy_value as:
lazy_value() => 5
Here is my half a day endeavor conclusion
var make_lazy = function () {
var innerFunction = null;
var array = [];
for (var i = 0; i < arguments.length; i++) {
if (typeof arguments[i] == 'function') {
innerFunction = arguments[i];
} else {
array.push(arguments[i]);
}
}
innerFunction.apply(innerFunction, array);
innerFunction();
};
I'm using arguments and apply() and think I am close? However I am getting TypeError: lazy_sum is not a function at Object.exports.runInThisContext within test results. Any help, especially understanding what is going on, is appreciated. Thanks
...
return function() {
return innerFunction.apply(this, array);
};
};
Thanks again all. Problem solved.
Related
I'm getting to grips with beginner methods of GScript now but so far have only used one function. Could someone show me how to 'call' another function to check for something and then return a TRUE or FALSE. Here is my attempt (it will eventually check a lot of things but I'm just checking one thing to start..)
Function callAnotherFunctionAndGetResult () {
MyResult = call(CheckTrueFalse)
if(MyResult = True then.. do something)
};
function CheckTrueFalse() {
if(3 > 2) {
CheckTrueFalse = TRUE
Else
CheckTrueFalse = FALSE
};
So basically I just want to get the other function to check something (in this case is 3 bigger than 2?) if it is then return TRUE. From this I should have the knowledge to modify for the real purpose. I'm used to Visual Basic so I've written it more how that would look - I know that won't work. Could someone help me convert so will work with Google Script please?
A function with a return statement is what you're looking for. Assuming you need the called function to take some input from the main function:
function mainFunction() {
//...
var that = "some variable found above";
//call other function with input and store result
var result = otherFunction(that);
if (result) {
//if result is true, do stuff
}
else {
//if result is false, do other stuff
}
}
function otherFunction(that) {
var this = "Something"; //check variable
return (this == that);
//(this == that) can be any conditional that evaluates to either true or false,
//The result then gets returned to the first function
}
You could also skip assigning the result variable and just check the returned condition directly, i.e.:
if (otherFunction(that)) {
//do stuff
}
else {do other stuff}
Let me know if you need me to clarify any of the syntax or if you have any more questions.
Here's a basic sample that might help you:
function petType(myPet){
return myPet;
}
function mainFunctoin(){
var newPet = petType("dog");
if(newPet === "dog"){
Logger.log("true");
}else{
Logger.log("false");
}
}
Execute mainFunction().
If you set petType to "cat", it will return false; but, if you set it to "dog", it will return true.
Let me know if it helped.
I am missing something fundamental in terms of callbacks/async in the code below: why do I get:
[,,'[ {JSON1} ]']
[,,'[ {JSON2} ]']
(=2 console returns) instead of only one console return with one proper table, which is want I want and would look like:
[,'[ {JSON1} ]','[ {JSON2} ]']
or ideally:
[{JSON1},{JSON2}]
See my code below, getPTdata is a function I created to retrieve some JSON via a REST API (https request). I cannot get everything at once since the API I'm talking to has a limit, hence the limit and offset parameters of my calls.
offsets = [0,1]
res = []
function goGetData(callback) {
for(var a = 0; a < offsets.length; a++){
getPTdata('stories',
'?limit=1&offset='+offsets[a]+'&date_format=millis',
function(result){
//called once getPTdata is done
res[a] = result
callback(res)
});
}
}
goGetData(function(notgoingtowork){
//called once goGetData is done
console.log(res)
})
Solved like this:
offsets = [0,1]
res = []
function goGetData(callback) {
var nb_returns = 0
for(var a = 0; a < offsets.length; a++){
getPTdata('stories','?limit=1&offset='+offsets[a]+'&date_format=millis', function(result){
//note because of "loop closure" I cannot use a here anymore
//called once getPTdata is done, therefore we know result and can store it
nb_returns++
res.push(JSON.parse(result))
if (nb_returns == offsets.length) {
callback(res)
}
});
}
}
goGetData(function(consolidated){
//called once goGetData is done
console.log(consolidated)
})
I have three functions that I have listed in an array. Now I need a random function of the three to be called when pressing a button. However, when I press the button it calls all three functions and I'm not quite sure where I've gone wrong. It looks like this right now:
function Arm1function1(){
this.parent.parent.parent.Armfront1.visible = true;
this.parent.parent.parent.Armback1.visible = false;
}
function Arm1function2(){
this.parent.parent.parent.Armfront1.visible = false;
this.parent.parent.parent.Armback1.visible = true;
}
function Arm1function3(){
this.parent.parent.parent.Armfront1.visible = false;
this.parent.parent.parent.Armback1.visible = false;
}
function getRandomElementOf(Armbuttonarray1:Array):Object {
var Armbuttonarray1:Array = [Arm1function1(), Arm1function2(), Arm1function3()];
var idx:int=Math.floor(Math.random() * Armbuttonarray1.length);
return Armbuttonarray1[idx];
}
Randombutton1part1.addEventListener(MouseEvent.CLICK, Randombutton1part1Click);
function Randombutton1part1Click(e:MouseEvent):void
{
getRandomElementOf(null);
}
Any clue of where I've gone wrong?
Your issue is this line:
var Armbuttonarray1:Array = [Arm1function1(), Arm1function2(), Arm1function3()];
When populating that array, you are actually populating it with the results of the functions.
Should be:
var Armbuttonarray1:Array = [Arm1function1, Arm1function2, Arm1function3];
Notice the lack of parenthesis ().
You want to actually execute the function on the click handler, so you'll need to tweak that a bit too:
getRandomElementOf(null)();
or
getRandomElementOf(null).call();
As an aside, your getRandomElementOf function should probably look more like this:
function getRandomElementOf(array:Array):Object {
return array[Math.floor(Math.random() * array.length)];
}
Then do:
getRandomElementOf([Arm1function1, Arm1function2, Arm1function3])();
I'm attempting to gradually refactor existing code. I have a set of functions that are defined, and only differ by one of the internal arguments:
function loadGame1():void
{
loadGame("save1");
}
function loadGame2():void
{
loadGame("save2");
}
function loadGame3():void
{
loadGame("save3");
}
//... snip many, many lines
// Note- I cannot pass function arguments at this time!
picker(loadGame1, loadGame2, loadGame3 ...);
I'm trying to refactor at least part of this (I can't completely replace the whole thing yet, too many interdependencies).
Basically, I want to be able to generate a big set of functions with the difference between the functions being a internal parameter:
var fNames:Array = new Array("save1", "save2", "save3");
var funcs:Array = new Array();
for (var i = 0; i < fNames.length; i += 1)
{
trace("Creating function with indice = ", i);
funcs.push(
function() : void
{
saveGame(fNames[i]);
}
)
}
picker(funcs[0], funcs[1], funcs[2] ...);
However, as I understand it, closure is causing the state of i to be maintained beyond the scope of the for loop, and any attempt to call any of the generated functions is failing with an out-of-bounds error, which is what you would expect given that i will reach fNames.size + 1 before i < fNames.size evaluates to false.
So, basically, given that I need to generate functions that are passed as arguments to a pre-existing function that I cannot change currently. How can I dynamically generate these functions?
Try to use IIFE:
for (var i = 0; i < fNames.length; i += 1)
{
(function(i){
trace("Creating function with indice = ", i);
funcs.push(
function() : void
{
saveGame(fNames[i]);
}
)
})(i);
}
Hai am Getting trouble to retrive the values from function(addText).i Called from another function onFullScreen().I dont know how Can i do this,Kindly Help me?Here i attach my Code
private function addText()
{
nc = new NetConnection();
nc.addEventListener(NetStatusEvent.NET_STATUS, ncOnStatus);
function ncOnStatus(infoObject:NetStatusEvent)
{
trace("nc: "+infoObject.info.code+" ("+infoObject.info.description+")");
if (infoObject.info.code == "NetConnection.Connect.Success")
{
initSharedObject(chatSharedObjectName);
}
}
function formatMessage(chatData:Object)
{
trace("room"+chatData.message);
number = chatData.txtalign;//i want to retrive the value of number
number.toString();
return number;
}
function syncEventHandler(ev:SyncEvent)
{
var infoObj:Object = ev.changeList;
// if first time only show last 4 messages in the list
if (lastChatId == 0)
{
lastChatId = Number(textchat_so.data["lastChatId"]) - 1;
if (lastChatId < 0)
lastChatId = 0;
}
}
function connectSharedObject(soName:String)
{
textchat_so = SharedObject.getRemote(soName, nc.uri)
// add new message to the chat box as they come in
textchat_so.addEventListener(SyncEvent.SYNC, syncEventHandler)
textchat_so.connect(nc)
}
function connectSharedObjectRes(soName:String)
{
connectSharedObject(soName)
trace(soName)
}
function initSharedObject(soName:String)
{
// initialize the shared object server side
nc.call("initSharedObject", new Responder(connectSharedObjectRes), soName)
}
}
i using the variable in another function ,but I cannot retrive the Value.
private function onFullScreen(event:FullScreenEvent):void
{
mediaContainer.addMediaElement(alert);
alert.alert("Error",number);// if i cannot retrive the value hnumber here
}
The addText() method is asynchronous, meaning that you can't simply call it , you need to wait for the event listener to return a value.
I'm not sure why you would feel the need to enclose all these functions, it's not very legible and I doubt it's necessary. You're also missing quite a few semi colons...
In any case , I couldn't see where the formatMessage() method was called, it seems that's the only place where the "number" variable gets defined.
You could create a variable outside the scope of the functions.
private var num:int;
Then in your addText function, assign a value to the variable:
num = infoObject.info.code;
Then in your onFullScreen function, access the num variable:
alert.alert("Error", num);