I am new to JavaScript.
<html>
<body>
<script type="text/javascript">
var x=5;
document.write(x);
document.write("<br />");
var x;
document.write(x);
</script>
</body>
</html>
Result is:
5
5
When x is declared the second time it should be undefined, but it keeps the previous value. Please explain whether this redeclaration has any special purpose.
You aren't really re-declaring the variable.
The variable statement in JavaScript, is subject to hoisting, that means that they are evaluated at parse-time and later in runtime the assignments are made.
Your code at the end of the parse phase, before the execution looks something like this:
var x;
x = 5;
document.write(x);
document.write("<br />");
document.write(x);
var alone does not perform an assignment. It only flags that when you use the variable name throughout the scope in which the var occurs, you are talking about a local variable and not global (the controversial default). The var is spotted when the function is parsed and holds throughout that scope, so where you put it is irrelevant:
var a= 0;
function foo() {
a= 1;
return a;
var a;
}
var b= foo();
alert('global a='+a+', local a='+b);
Results in global a= 0, local a= 1: even though the var statement is never reached in the course of execution of foo(), it is still effective in making a a local variable.
So declaring var x a second time in the same scope is completely redundant. However you might sometimes still do it, typically when you re-use a local variable name for a second independent use within the same function. Most commonly:
for (var i= 0; i<onething.length; i++) {
...do some trivial loop...
}
for (var i= 0; i<anotherthing.length; i++) {
...do another trivial loop...
}
Whilst you could certainly omit the second var, and tools like jslint would demand you do so, it might not actually be a good idea.
Imagine you later change or remove the first loop so that it no longer declares i to be var. Now the remaining second loop suddenly changes meaning from a local to a global variable. If you fail to notice when updating the first loop that the second loop has a hidden dependency on it (and you might very well fail to notice that given how the eyes elide the pattern for(...=0 ; ...<...; ...++) into “oh, that's just a standard iterator”), you've got a subtle and annoying-to-debug problem.
so when the second time when its declared x should be undefined
What part of the specification says this?
"Undefined behaviour" does not mean "the variable will be undefined".
As far as my understanding of javascript goes, the use of the var keyword is completely optional in the global scope. It's a different story for functions.
When inside a function, use the var keyword to indicate that the variable is local to the function (as opposed to being global by default).
I personally use var in the global scope to show that a variable is being declared and/or utilized for the first time.
You can reference http://www.w3schools.com/js/js_variables.asp for more info.
That second var x is totally superfluous.
Within the same scope, it is totally unnecessary to "redeclare" a variable.
Also, a programmer might want to use var to localize a variable:
<script>
var x= 'this is global x';
function my_x() {
var x= 'localized x';
alert(x);
}
my_x();
alert(x);
</script>
You should never redeclare a variable within the same scope, if you really want to change this then assign to it. Redeclaration is not required to create a different object in this dynamic language, if you want x to be a string just assign:
x = "hello";
It is not required that you set it back to undefined or redeclare first.
Please note that changing the variable type is not very good practice in most situations, simply stating that it is a possibility if that's what you require.
I recently wrote code like:
var obj1 = get_an_object();
var v = obj1.get_velocity();
v += changes_in_velocity();
obj1.set_velocity(v);
var obj2 = get_an_object();
var v = obj2.get_velocity();
v += changes_in_velocity();
obj2.set_velocity(v);
(The actual code was more complicated and less repetitive)
So far as the browser is concerned, the second var v statement was redundant and pointless. To me, it served two purposes. It said to forget everything I knew about the old v, because this was a new usage. And it meant I could re-order the code, or comment out the first half, without breaking things.
Related
if i write something like this:
var a = 1;
function lol(){
console.log(a);
}
lol();
it outputs 1 as intended, as i initialized a=1 in global scope. So i thought in function it initialized its value as well.
But when i write something like this:
var a = 1;
function lol(){
var a = a + a;
console.log(a);
}
lol();
it outputs NaN, which confuses me, cuz i thought the variable has already been initialized in global scope.
Here's my thoughts, don't know if it's correct or not, so i'm asking: i think the keywords like var/let/const, each time it's mentioned, it kind of re-initialize the variable or what? and since the second var is in block scope, so when mentioned with var, the variable a goes initialized again and thus becomes undefined, outputs NaN.
am i correct? plz help.
You initialize the variable then just use the same variable
var a = 1;
function lol(){
a = a + a;
console.log(a);
}
lol();
at statement var a = a + a; you are defining altogether different variable which was not initialize before arithmetic operation so it is resulting NaN compiler declared another variable with same name a
Maybe it's happening because of hoisting. Please refer https://developer.mozilla.org/en-US/docs/Glossary/Hoisting#var_hoisting
As per MDN,
JavaScript Hoisting refers to the process whereby the interpreter appears to move the declaration of functions, variables or classes to the top of their scope, prior to execution of the code.
Today, I got completely surprised when I saw that a global variable has undefined value in a certain case.
Example:
var value = 10;
function test() {
//A
console.log(value);
var value = 20;
//B
console.log(value);
}
test();
Gives output as
undefined
20
Here, why is the JavaScript engine considering global value as undefined? I know that JavaScript is an interpreted language. How is it able to consider variables in the function?
Is that a pitfall from the JavaScript engine?
This phenomenon is known as: JavaScript Variable Hoisting.
At no point are you accessing the global variable in your function; you're only ever accessing the local value variable.
Your code is equivalent to the following:
var value = 10;
function test() {
var value;
console.log(value);
value = 20;
console.log(value);
}
test();
Still surprised you're getting undefined?
Explanation:
This is something that every JavaScript programmer bumps into sooner or later. Simply put, whatever variables you declare are always hoisted to the top of your local closure. So, even though you declared your variable after the first console.log call, it's still considered as if you had declared it before that.
However, only the declaration part is being hoisted; the assignment, on the other hand, is not.
So, when you first called console.log(value), you were referencing your locally declared variable, which has got nothing assigned to it yet; hence undefined.
Here's another example:
var test = 'start';
function end() {
test = 'end';
var test = 'local';
}
end();
alert(test);
What do you think this will alert? No, don't just read on, think about it. What's the value of test?
If you said anything other than start, you were wrong. The above code is equivalent to this:
var test = 'start';
function end() {
var test;
test = 'end';
test = 'local';
}
end();
alert(test);
so that the global variable is never affected.
As you can see, no matter where you put your variable declaration, it is always hoisted to the top of your local closure.
Side note:
This also applies to functions.
Consider this piece of code:
test("Won't work!");
test = function(text) { alert(text); }
which will give you a reference error:
Uncaught ReferenceError: test is not defined
This throws off a lot of developers, since this piece of code works fine:
test("Works!");
function test(text) { alert(text); }
The reason for this, as stated, is because the assignment part is not hoisted. So in the first example, when test("Won't work!") was run, the test variable has already been declared, but has yet to have the function assigned to it.
In the second example, we're not using variable assignment. Rather, we're using proper function declaration syntax, which does get the function completely hoisted.
Ben Cherry has written an excellent article on this, appropriately titled JavaScript Scoping and Hoisting.
Read it. It'll give you the whole picture in full detail.
I was somewhat disappointed that the problem here is explained, but no one proposed a solution. If you want to access a global variable in function scope without the function making an undefined local var first, reference the var as window.varName
Variables in JavaScript always have function-wide scope. Even if they were defined in the middle of the function, they are visible before. Similar phenomena may be observed with function hoisting.
That being said, the first console.log(value) sees the value variable (the inner one which shadows the outer value), but it has not yet been initialized. You can think of it as if all variable declarations were implicitly moved to the beginning of the function (not inner-most code block), while the definitions are left on the same place.
See also
Javascript function scoping and hoisting
Javascript variable declarations at the head of a function
There is a global variable value, but when control enters the test function, another value variable is declared, which shadows the global one. Since variable declarations (but not assignments) in JavaScript are hoisted to the top of scope in which they are declared:
//value == undefined (global)
var value = 10;
//value == 10 (global)
function test() {
//value == undefined (local)
var value = 20;
//value == 20 (local)
}
//value == 10 (global)
Note that the same is true of function declarations, which means you can call a function before it appears to be defined in your code:
test(); //Call the function before it appears in the source
function test() {
//Do stuff
}
It's also worth noting that when you combine the two into a function expression, the variable will be undefined until the assignment takes place, so you can't call the function until that happens:
var test = function() {
//Do stuff
};
test(); //Have to call the function after the assignment
The simplest way to keep access to outer variables (not just of global scope) is, of course, to try to not re-declare them under the same name in functions; just do not use var there. The use of proper descriptive naming rules is advised. With those, it will be hard to end up with variables named like value (this aspect is not necessarily related to the example in the question as this variable name might have been given for simplicity).
If the function might be reused elsewhere and hence there is no guarantee that the outer variable actually defined in that new context, Eval function can be used. It is slow in this operation so it is not recommended for performance-demanding functions:
if (typeof variable === "undefined")
{
eval("var variable = 'Some value';");
}
If the outer scope variable you want access to is defined in a named function, then it might be attached to the function itself in the first place and then accessed from anywhere in the code -- be it from deeply nested functions or event handlers outside of everything else. Notice that accessing properties is way slower and would require you to change the way you program, so it is not recommended unless it is really necessary: Variables as properties of functions (JSFiddle):
// (the wrapper-binder is only necessary for using variables-properties
// via "this"instead of the function's name)
var functionAsImplicitObjectBody = function()
{
function someNestedFunction()
{
var redefinableVariable = "redefinableVariable's value from someNestedFunction";
console.log('--> functionAsImplicitObjectBody.variableAsProperty: ', functionAsImplicitObjectBody.variableAsProperty);
console.log('--> redefinableVariable: ', redefinableVariable);
}
var redefinableVariable = "redefinableVariable's value from someFunctionBody";
console.log('this.variableAsProperty: ', this.variableAsProperty);
console.log('functionAsImplicitObjectBody.variableAsProperty: ', functionAsImplicitObjectBody.variableAsProperty);
console.log('redefinableVariable: ', redefinableVariable);
someNestedFunction();
},
functionAsImplicitObject = functionAsImplicitObjectBody.bind(functionAsImplicitObjectBody);
functionAsImplicitObjectBody.variableAsProperty = "variableAsProperty's value, set at time stamp: " + (new Date()).getTime();
functionAsImplicitObject();
// (spread-like operator "..." provides passing of any number of arguments to
// the target internal "func" function in as many steps as necessary)
var functionAsExplicitObject = function(...arguments)
{
var functionAsExplicitObjectBody = {
variableAsProperty: "variableAsProperty's value",
func: function(argument1, argument2)
{
function someNestedFunction()
{
console.log('--> functionAsExplicitObjectBody.variableAsProperty: ',
functionAsExplicitObjectBody.variableAsProperty);
}
console.log("argument1: ", argument1);
console.log("argument2: ", argument2);
console.log("this.variableAsProperty: ", this.variableAsProperty);
someNestedFunction();
}
};
return functionAsExplicitObjectBody.func(...arguments);
};
functionAsExplicitObject("argument1's value", "argument2's value");
I was running into the same problem even with global variables. My problem, I discovered, was global variable do Not persist between html files.
<script>
window.myVar = 'foo';
window.myVarTwo = 'bar';
</script>
<object type="text/html" data="/myDataSource.html"></object>
I tried to reference myVar and myVarTwo in the loaded HTML file, but received the undefined error.
Long story/day short, I discovered I could reference the variables using:
<!DOCTYPE html>
<html lang="en">
<!! other stuff here !!>
<script>
var myHTMLVar = this.parent.myVar
/* other stuff here */
</script>
</html>
Is this a variable definition or declaration? And why?
var x;
..and is the memory reserved for x after this statement?
EDIT:
In C extern int x; is a declaration, int x = 5; is a definition. What's the analog in JS? Wikipedia says a declaration allocates memory and the definition assigns a value to this allocated memory.
SECOND EDIT:
I think the explanation of #Deryck sounds great, but there's some output that disagrees with his explanation:
> var x;
undefined
> x
undefined // now it looks like x is defined to the value undefined
> y
ReferenceError: y is not defined
If the ReferenceError output would say y is not declared it would make sense. But often I read that JS has two non-values: null and undefined. So var x would be a definition with the value undefined.
var x is a declaration because you are not defining what value it holds but you are declaring its existence and the need for memory allocation.
var x = 1 is both declaration and definition but are separated with x being declared in the beginning while its definition comes at the line specified (variable assignments happen inline).
I see that you already understand the concept of hoisting but for those that don't, Javascript takes every variable and function declaration and brings it to the top (of its corresponding scope) then trickles down assigning them in order.
You seem to know most of this already though. Here's a great resource if you want some advanced, in-depth exploration. Yet I have a feeling you've been there before.
Javascript Garden
PS - your analogy between C variable dec/def and JS was spot on. What you read on Wikipedia was correct.
Declaring a variable is like telling the (javascript) compiler that this token x is something I want to use later. It does point to a location in memory, but it does not yet contain a value. ie. it is undefined
var x;
defining it means to give it a value which you can either do it like:
x = 10; // defining a variable that was declared previously
or like this:
var y = 20; // declaring and defining a variable altogether.
http://msdn.microsoft.com/en-us/library/67defydd(v=vs.94).aspx
http://www.w3schools.com/js/js_variables.asp
I will give you a long answer for better explanation.
When the javascript engine is not able to find a particular variable in memory, it will throw an error. To be more specific, when the javascript engine (Execution Context) is not able to "reference" a variable in memory, it will throw a ReferenceError. This is not exactly the same as a Declaration Error, at least in javascript.
There is a deference between a not defined error and the value undefined.
So doing
var a = undefined;
and
var a;
will both log the same result i.e. undefined. This is because, when you simply do a var a; the javascript engine allocates memory for the variable and automatically sets it's value to undefined, which is different from saying that a doesn't exist at all - in which case it will throw a ReferenceError.
Hoisting
console.log(a); // undefined
var a = 'something';
will log undefined because, the javascript engine knows there's a variable declared somewhere in the code - which means to say that the javascript engine actually does something before it executes the code - one of the thing it does is hoists variables. To put it simply, the above code is the same as
var a; // hoisted (declared and defined the value `undefined`)
console.log(a); // undefined
a = 'something' // update the defined value to `something`
So, yes, declaration and definition happen together in javascript (automatically - if you don't do it yourself) and the default defined value is undefined.
ES6
Just an additional note
const a;
will throw a SyntaxError where a initializer (definition) is necessary. const is the only time when you need to declare and define manually.
> var x;
undefined
> x
undefined // now it looks like x is defined to the value undefined
> y
ReferenceError: y is not defined
Although it is usually said that Javascript is an interpreted language, but there is also a compilation step that happens very fast just before the interpreter runs. The job of this compilation step is to create scope chains, where variables are declared(no read/write operation here, just simple name-keeping) in their respective scopes. These variables will point to some memory location but value in it will be undefined until some execution is carried out by the interpreter.
> Compiler run:
When compiler sees var x;, it will simply book-keep this variable in its respective scope.
The next x; and y; are simply ignored in the compilation step as they are execution statements.
> Interpreter run:
When interpreter sees var x;, it will skip this as there is no read/write operation here.
Now when interpreter sees x;(execution statement), "x" will already be declared in the scope, and it will hold value "undefined", which is what you get on the console.
But when interpreter sees y; similarly, there has been no previous declaration or name-keeping for it in the compilation step, and thus we get the ReferenceError as expected.
Hope someone finds this comment useful.
var x, y, z;
var x;
var h = 4;
i = 4;
all the above are global variables if placed at the top, (outside any functions)
Lets say that the javascript has a function start
function start() {
x = 5*5;
}
the global variable x is now equal to 25
Where as if the var x; was not placed outside of any functions, that variable x would just be local to that function.
You declare JavaScript variables with the var keyword:
var carname;
After the declaration, the variable is empty (it has no value).
To assign a value to the variable, use the equal sign
var carname="Volvo";
In computer programs, variables are often declared without a value. The value can be something that has to be calculated, or something that will be provided later, like user input. Variable declared without a value will have the value undefined.
The variable carname will have the value undefined after the execution of the following statement:
var carname;
var hoisting
In JavaScript, a variable can be declared after being used.
bla = 2
var bla;
// ...
// is implicitly understood as:
var bla;
bla = 2;
For that reason, it is recommended to always declare variable at the top of functions. Otherwise, it may lead to confusing cases
When declaring a variable without assigning a value to it, there still needs to be some memory available for it, otherwise you cannot make a reference to the variable later in the program. I don't think it's a noticeable amount of memory being used and won't make a difference.
var x;
This is a variable declaration. In Js if you don't assign any value to variable in declaration. It will get undefined by default.
var x; // declaring x
console.log(x); // output: undefined
But if you have not even declared the variable in you try to access it. It says that the variable is not defined.
console.log(y); // Output: ReferenceError: y is not defined
If you need access to objects between JS files, it's good practice to expose one object to the global namespace and declare fields and methods on that object.
File 1:
var myObject;
myObject.myField = "Field!";
File 2:
myObject.prototype.myFunction = function () {
return this.myField;
};
I have taken from a really good discussion on : Equivalent of C extern declaration in JavaScript
https://github.com/ganqqwerty/123-Essential-JavaScript-Interview-Questions
Various trivia regarding the difference between undefined and null completely aside, the short answer is: there is no equivalence in Javascript. There are no bare "forward declarations". Javascript variable declarations are definitions. Variables that have been defined but not explicitly initialized will contain the value 'undefined'. There is no "external linkage".
If you refer to an identifier that is not in any accessible scope (perhaps because it doesn't exist the first place), you will get your "ReferenceError: y is not defined". This has nothing to do with variable value or storage.
In simple terms,
undefined means value to the variable is not defined.
not defined means the variable itself is not defined.
var x; //value is not defined. So,
x //undefined
//y variable is not declared or defined. So,
y // y is not defined
I want to know what's the difference when declare a variable whether using var. i used the following code:
<body>
<h1>New Web Project Page</h1>
<script type="text/javascript">
function test(){
a = "hello";
var b="world";
}
alert(a);
alert(b);
</script>
</body>
Why the alert doesn't work and what's the difference when declare a variable whether using var in javascript.
alert doesn't work because, in the case of b, it doesn't exist in the correct scope and in the case of a it hasn't been instantiated yet because you haven't called the function test
var creates a variable which is local to the scope in which it is called. Without var you create a global variable.
function fn ( ) {
var x = 0; // this variable is local to the function fn
y = 10; // this variable is global and can be accessed
// from anywhere after you call fn
}
generally speaking, unless there is a good reason you don't want to use global variables. That is to say, you want to create all of your variables using var. Putting variables only in the scope they are needed makes for easier to understand and maintain code. It also helps to alleviate the "Magic Variable" problem. Where you have variables that just appear but you don't have a clear idea of from where. It also makes it easier to debug your code because, in javascript, variables that don't exist get created on the fly. But if you only use local variables through var and a tool like jsLint you won't run into the problem of a misspelling in a variable name throwing your code out of wack.
Declaring a variable without var makes it global so anything can access it. The reason your alert doesn't work however is due to you never calling test() so a or b are never assigned. If you do call test (before the alerts), b will be undefined, and a should read hello.
A great resource on variables and scoping.
You're not invoking the test() function. When the var is excluded, variables become global, so they're available to all code.
Exact same question regarding use of 'var' has been answered here
Regarding why your alert doesn't work, it is because you haven't called the 'test()' function. It has just been created...it will do nothing. You'll need to call it in order to populate the variables.
Today, I got completely surprised when I saw that a global variable has undefined value in a certain case.
Example:
var value = 10;
function test() {
//A
console.log(value);
var value = 20;
//B
console.log(value);
}
test();
Gives output as
undefined
20
Here, why is the JavaScript engine considering global value as undefined? I know that JavaScript is an interpreted language. How is it able to consider variables in the function?
Is that a pitfall from the JavaScript engine?
This phenomenon is known as: JavaScript Variable Hoisting.
At no point are you accessing the global variable in your function; you're only ever accessing the local value variable.
Your code is equivalent to the following:
var value = 10;
function test() {
var value;
console.log(value);
value = 20;
console.log(value);
}
test();
Still surprised you're getting undefined?
Explanation:
This is something that every JavaScript programmer bumps into sooner or later. Simply put, whatever variables you declare are always hoisted to the top of your local closure. So, even though you declared your variable after the first console.log call, it's still considered as if you had declared it before that.
However, only the declaration part is being hoisted; the assignment, on the other hand, is not.
So, when you first called console.log(value), you were referencing your locally declared variable, which has got nothing assigned to it yet; hence undefined.
Here's another example:
var test = 'start';
function end() {
test = 'end';
var test = 'local';
}
end();
alert(test);
What do you think this will alert? No, don't just read on, think about it. What's the value of test?
If you said anything other than start, you were wrong. The above code is equivalent to this:
var test = 'start';
function end() {
var test;
test = 'end';
test = 'local';
}
end();
alert(test);
so that the global variable is never affected.
As you can see, no matter where you put your variable declaration, it is always hoisted to the top of your local closure.
Side note:
This also applies to functions.
Consider this piece of code:
test("Won't work!");
test = function(text) { alert(text); }
which will give you a reference error:
Uncaught ReferenceError: test is not defined
This throws off a lot of developers, since this piece of code works fine:
test("Works!");
function test(text) { alert(text); }
The reason for this, as stated, is because the assignment part is not hoisted. So in the first example, when test("Won't work!") was run, the test variable has already been declared, but has yet to have the function assigned to it.
In the second example, we're not using variable assignment. Rather, we're using proper function declaration syntax, which does get the function completely hoisted.
Ben Cherry has written an excellent article on this, appropriately titled JavaScript Scoping and Hoisting.
Read it. It'll give you the whole picture in full detail.
I was somewhat disappointed that the problem here is explained, but no one proposed a solution. If you want to access a global variable in function scope without the function making an undefined local var first, reference the var as window.varName
Variables in JavaScript always have function-wide scope. Even if they were defined in the middle of the function, they are visible before. Similar phenomena may be observed with function hoisting.
That being said, the first console.log(value) sees the value variable (the inner one which shadows the outer value), but it has not yet been initialized. You can think of it as if all variable declarations were implicitly moved to the beginning of the function (not inner-most code block), while the definitions are left on the same place.
See also
Javascript function scoping and hoisting
Javascript variable declarations at the head of a function
There is a global variable value, but when control enters the test function, another value variable is declared, which shadows the global one. Since variable declarations (but not assignments) in JavaScript are hoisted to the top of scope in which they are declared:
//value == undefined (global)
var value = 10;
//value == 10 (global)
function test() {
//value == undefined (local)
var value = 20;
//value == 20 (local)
}
//value == 10 (global)
Note that the same is true of function declarations, which means you can call a function before it appears to be defined in your code:
test(); //Call the function before it appears in the source
function test() {
//Do stuff
}
It's also worth noting that when you combine the two into a function expression, the variable will be undefined until the assignment takes place, so you can't call the function until that happens:
var test = function() {
//Do stuff
};
test(); //Have to call the function after the assignment
The simplest way to keep access to outer variables (not just of global scope) is, of course, to try to not re-declare them under the same name in functions; just do not use var there. The use of proper descriptive naming rules is advised. With those, it will be hard to end up with variables named like value (this aspect is not necessarily related to the example in the question as this variable name might have been given for simplicity).
If the function might be reused elsewhere and hence there is no guarantee that the outer variable actually defined in that new context, Eval function can be used. It is slow in this operation so it is not recommended for performance-demanding functions:
if (typeof variable === "undefined")
{
eval("var variable = 'Some value';");
}
If the outer scope variable you want access to is defined in a named function, then it might be attached to the function itself in the first place and then accessed from anywhere in the code -- be it from deeply nested functions or event handlers outside of everything else. Notice that accessing properties is way slower and would require you to change the way you program, so it is not recommended unless it is really necessary: Variables as properties of functions (JSFiddle):
// (the wrapper-binder is only necessary for using variables-properties
// via "this"instead of the function's name)
var functionAsImplicitObjectBody = function()
{
function someNestedFunction()
{
var redefinableVariable = "redefinableVariable's value from someNestedFunction";
console.log('--> functionAsImplicitObjectBody.variableAsProperty: ', functionAsImplicitObjectBody.variableAsProperty);
console.log('--> redefinableVariable: ', redefinableVariable);
}
var redefinableVariable = "redefinableVariable's value from someFunctionBody";
console.log('this.variableAsProperty: ', this.variableAsProperty);
console.log('functionAsImplicitObjectBody.variableAsProperty: ', functionAsImplicitObjectBody.variableAsProperty);
console.log('redefinableVariable: ', redefinableVariable);
someNestedFunction();
},
functionAsImplicitObject = functionAsImplicitObjectBody.bind(functionAsImplicitObjectBody);
functionAsImplicitObjectBody.variableAsProperty = "variableAsProperty's value, set at time stamp: " + (new Date()).getTime();
functionAsImplicitObject();
// (spread-like operator "..." provides passing of any number of arguments to
// the target internal "func" function in as many steps as necessary)
var functionAsExplicitObject = function(...arguments)
{
var functionAsExplicitObjectBody = {
variableAsProperty: "variableAsProperty's value",
func: function(argument1, argument2)
{
function someNestedFunction()
{
console.log('--> functionAsExplicitObjectBody.variableAsProperty: ',
functionAsExplicitObjectBody.variableAsProperty);
}
console.log("argument1: ", argument1);
console.log("argument2: ", argument2);
console.log("this.variableAsProperty: ", this.variableAsProperty);
someNestedFunction();
}
};
return functionAsExplicitObjectBody.func(...arguments);
};
functionAsExplicitObject("argument1's value", "argument2's value");
I was running into the same problem even with global variables. My problem, I discovered, was global variable do Not persist between html files.
<script>
window.myVar = 'foo';
window.myVarTwo = 'bar';
</script>
<object type="text/html" data="/myDataSource.html"></object>
I tried to reference myVar and myVarTwo in the loaded HTML file, but received the undefined error.
Long story/day short, I discovered I could reference the variables using:
<!DOCTYPE html>
<html lang="en">
<!! other stuff here !!>
<script>
var myHTMLVar = this.parent.myVar
/* other stuff here */
</script>
</html>