for the sake of fun and exploring nodeJS I made an object
var f15c = {
fuel : 10000,
IRST: true,
AESA: true,
speed: 2500,
Ammo:
{
AMRAAM: 6,
Python5: 2,
Delilah: 3,
},
tailnumber : the question begins here.
}
The problem came when I wanted to add tailnumber that is not the same for every plane but should be assigned to the plane.
what is the methode?
var f15c = {
...
tailnumber = function (tn){"whats should i add here?"}
}
or
var f15c = {
...
tailnumber: ?? what should i place here?
SetTailNumber = function(tn)
{
tailnumber=tn;
}
}
or must I have the entire F15c as a function?
var f15c = function(tn) {
...
tailnumber = tn;
but then i cannot set the entire variables complex.
or perhaps I'm doing it wrong and should refer the variable as an individual F15 and use a different function to create it?
but then how do I make that field in a way it is unassigned and waiting to be assigned (and then saves the assigned number)?
would appreciate some heads up
The secret is to use this to refer to a property of the own object
var f15c = {
...
tailnumber: null,
setTailNumber : function(tn)
{
this.tailnumber=tn;
}
}
Then:
f15c.setTailNumber(1234);
console.log(f15c.tailnumber);
Do you mean you want to set a value to a property?
var f15c = {
_tailnumber: 0,
set tailnumber(newtailnumber) {
this._tailnumber = newtailnumber;
},
get tailnumber() {
return this._tailnumber
}
};
f15c.tailnumber = "304";
console.log(f15c.tailnumber);
console.log(f15c);
Why does the following work?
<something>.stop().animate(
{ 'top' : 10 }, 10
);
Whereas this doesn't work:
var thetop = 'top';
<something>.stop().animate(
{ thetop : 10 }, 10
);
To make it even clearer: At the moment I'm not able to pass a CSS property to the animate function as a variable.
{ thetop : 10 } is a valid object literal. The code will create an object with a property named thetop that has a value of 10. Both the following are the same:
obj = { thetop : 10 };
obj = { "thetop" : 10 };
In ES5 and earlier, you cannot use a variable as a property name inside an object literal. Your only option is to do the following:
var thetop = "top";
// create the object literal
var aniArgs = {};
// Assign the variable property name with a value of 10
aniArgs[thetop] = 10;
// Pass the resulting object to the animate method
<something>.stop().animate(
aniArgs, 10
);
ES6 defines ComputedPropertyName as part of the grammar for object literals, which allows you to write the code like this:
var thetop = "top",
obj = { [thetop]: 10 };
console.log(obj.top); // -> 10
You can use this new syntax in the latest versions of each mainstream browser.
With ECMAScript 2015 you are now able to do it directly in object declaration with the brackets notation:
var obj = {
[key]: value
}
Where key can be any sort of expression (e.g. a variable) returning a value.
So here your code would look like:
<something>.stop().animate({
[thetop]: 10
}, 10)
Where thetop will be evaluated before being used as key.
ES5 quote that says it should not work
Note: rules have changed for ES6: https://stackoverflow.com/a/2274327/895245
Spec: http://www.ecma-international.org/ecma-262/5.1/#sec-11.1.5
PropertyName :
IdentifierName
StringLiteral
NumericLiteral
[...]
The production PropertyName : IdentifierName is evaluated as follows:
Return the String value containing the same sequence of characters as the IdentifierName.
The production PropertyName : StringLiteral is evaluated as follows:
Return the SV [String value] of the StringLiteral.
The production PropertyName : NumericLiteral is evaluated as follows:
Let nbr be the result of forming the value of the NumericLiteral.
Return ToString(nbr).
This means that:
{ theTop : 10 } is the exact same as { 'theTop' : 10 }
The PropertyName theTop is an IdentifierName, so it gets converted to the 'theTop' string value, which is the string value of 'theTop'.
It is not possible to write object initializers (literals) with variable keys.
The only three options are IdentifierName (expands to string literal), StringLiteral, and NumericLiteral (also expands to a string).
ES6 / 2020
If you're trying to push data to an object using "key:value" from any other source, you can use something like this:
let obj = {}
let key = "foo"
let value = "bar"
obj[`${key}`] = value
// A `console.log(obj)` would return:
// {foo: "bar}
// A `typeof obj` would return:
// "object"
Hope this helps someone :)
I have used the following to add a property with a "dynamic" name to an object:
var key = 'top';
$('#myElement').animate(
(function(o) { o[key]=10; return o;})({left: 20, width: 100}),
10
);
key is the name of the new property.
The object of properties passed to animate will be {left: 20, width: 100, top: 10}
This is just using the required [] notation as recommended by the other answers, but with fewer lines of code!
Adding square bracket around the variable works good for me. Try this
var thetop = 'top';
<something>.stop().animate(
{ [thetop] : 10 }, 10
);
You can also try like this:
const arr = [{
"description": "THURSDAY",
"count": "1",
"date": "2019-12-05"
},
{
"description": "WEDNESDAY",
"count": "0",
"date": "2019-12-04"
}]
const res = arr.map(value => {
return { [value.description]: { count: value.count, date: value.date } }
})
console.log(res);
I couldn't find a simple example about the differences between ES6 and ES5, so I made one. Both code samples create exactly the same object. But the ES5 example also works in older browsers (like IE11), wheres the ES6 example doesn't.
ES6
var matrix = {};
var a = 'one';
var b = 'two';
var c = 'three';
var d = 'four';
matrix[a] = {[b]: {[c]: d}};
ES5
var matrix = {};
var a = 'one';
var b = 'two';
var c = 'three';
var d = 'four';
function addObj(obj, key, value) {
obj[key] = value;
return obj;
}
matrix[a] = addObj({}, b, addObj({}, c, d));
Update: As a commenter pointed out, any version of JavaScript that supports arrow functions will also support ({[myKey]:myValue}), so this answer has no actual use-case (and, in fact, it might break in some bizarre corner-cases).
Don't use the below-listed method.
I can't believe this hasn't been posted yet: just use arrow functions with anonymous evaluation!
Completely non-invasive, doesn't mess with the namespace, and it takes just one line:
myNewObj = ((k,v)=>{o={};o[k]=v;return o;})(myKey,myValue);
demo:
var myKey="valueof_myKey";
var myValue="valueof_myValue";
var myNewObj = ((k,v)=>{o={};o[k]=v;return o;})(myKey,myValue);
console.log(myNewObj);
useful in environments that don't support the new {[myKey]: myValue} syntax yet, such as—apparently; I just verified it on my Web Developer Console—Firefox 72.0.1, released 2020-01-08. I stand corrected; just wrap the thing in parenthesis and it works.
(I'm sure you could potentially make some more powerful/extensible solutions or whatever involving clever use of reduce, but at that point you'd probably be better served by just breaking out the Object-creation into its own function instead of compulsively jamming it all inline)
not that it matters since OP asked this ten years ago, but for completeness' sake and to demonstrate how it is exactly the answer to the question as stated, I'll show this in the original context:
var thetop = 'top';
<something>.stop().animate(
((k,v)=>{o={};o[k]=v;return o;})(thetop,10), 10
);
Given code:
var thetop = 'top';
<something>.stop().animate(
{ thetop : 10 }, 10
);
Translation:
var thetop = 'top';
var config = { thetop : 10 }; // config.thetop = 10
<something>.stop().animate(config, 10);
As you can see, the { thetop : 10 } declaration doesn't make use of the variable thetop. Instead it creates an object with a key named thetop. If you want the key to be the value of the variable thetop, then you will have to use square brackets around thetop:
var thetop = 'top';
var config = { [thetop] : 10 }; // config.top = 10
<something>.stop().animate(config, 10);
The square bracket syntax has been introduced with ES6. In earlier versions of JavaScript, you would have to do the following:
var thetop = 'top';
var config = (
obj = {},
obj['' + thetop] = 10,
obj
); // config.top = 10
<something>.stop().animate(config, 10);
2020 update/example...
A more complex example, using brackets and literals...something you may have to do for example with vue/axios. Wrap the literal in the brackets, so
[ ` ... ` ]
{
[`filter[${query.key}]`]: query.value, // 'filter[foo]' : 'bar'
}
ES5 implementation to assign keys is below:
var obj = Object.create(null),
objArgs = (
(objArgs = {}),
(objArgs.someKey = {
value: 'someValue'
}), objArgs);
Object.defineProperties(obj, objArgs);
I've attached a snippet I used to convert to bare object.
var obj = {
'key1': 'value1',
'key2': 'value2',
'key3': [
'value3',
'value4',
],
'key4': {
'key5': 'value5'
}
}
var bareObj = function(obj) {
var objArgs,
bareObj = Object.create(null);
Object.entries(obj).forEach(function([key, value]) {
var objArgs = (
(objArgs = {}),
(objArgs[key] = {
value: value
}), objArgs);
Object.defineProperties(bareObj, objArgs);
});
return {
input: obj,
output: bareObj
};
}(obj);
if (!Object.entries) {
Object.entries = function(obj){
var arr = [];
Object.keys(obj).forEach(function(key){
arr.push([key, obj[key]]);
});
return arr;
}
}
console(bareObj);
If you want object key to be same as variable name, there's a short hand in ES 2015.
New notations in ECMAScript 2015
var thetop = 10;
var obj = { thetop };
console.log(obj.thetop); // print 10
You can do it this way:
var thetop = 'top';
<something>.stop().animate(
new function() {this[thetop] = 10;}, 10
);
This way also you can achieve desired output
var jsonobj={};
var count=0;
$(document).on('click','#btnadd', function() {
jsonobj[count]=new Array({ "1" : $("#txtone").val()},{ "2" : $("#txttwo").val()});
count++;
console.clear();
console.log(jsonobj);
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<span>value 1</span><input id="txtone" type="text"/>
<span>value 2</span><input id="txttwo" type="text"/>
<button id="btnadd">Add</button>
You could do the following for ES5:
var theTop = 'top'
<something>.stop().animate(
JSON.parse('{"' + theTop + '":' + JSON.stringify(10) + '}'), 10
)
Or extract to a function:
function newObj (key, value) {
return JSON.parse('{"' + key + '":' + JSON.stringify(value) + '}')
}
var theTop = 'top'
<something>.stop().animate(
newObj(theTop, 10), 10
)
Given class Foo
class Foo
{
public function new(foo:Int, bar:Int, foobar:Int) {}
}
Retrieve number of arguments accepted by new. I've tried using #:rtti - then I tried
for(field in haxe.rtti.Rtti.getRtti(Foo).fields) {
if (field.name == "new") {
trace(field.type);
}
}
The result was promising
**
TestAll.hx:246: CFunction({
length : 3,
h : {
item : {
name : foo,
opt : false,
t : CAbstract(<...>,<...>),
value : null
},
next : {
item : {
name : <...>,
opt : <...>,
t : <...>,
value : null
},
next : {
item : <...>,
next : null
}
}
},
q : {
item : {
name : foobar,
opt : false,
t : CAbstract(<...>,<...>),
value : null
},
next : null
}
},CAbstract(Void,{
length : 0
}))**
So I tried field.type.length.
test/TestAll.hx:246: characters 14-31 : haxe.rtti.CType has no field
length
After a quick glance at http://api.haxe.org/haxe/rtti/CType.html#CFunction ,
I can see
CFunction(args:List<FunctionArgument>, ret:CType)
??? I'm baffled - it contains a List, yet it only returns CType? How to get to the information I want?
Thank you.
PS. I don't want macro solution, this is used inside unit test, and the generation of the construction itself is already macro heavy.
CType is an enum, and CFunction is one of the possible enum values (or "enum constructors").
You can see the source code here: https://github.com/HaxeFoundation/haxe/blob/development/std/haxe/rtti/CType.hx#L42-L51
You'll need to use a switch statement to dive into it and get your list:
switch (field.type) {
case CFunction(args,returnType):
trace(args.length);
default:
// Do nothing
}
To learn more I recommend these manual pages:
Enums
Pattern matching (switch statements)
I need a dynamic variable in nodejs .
I use the allocine-api, and she return, a different object when I use it . For example :
allocine.api(type, {code: code}, function(error, result) {
if(error){
console.log('Error : '+ error);
return;
}
socket.emit("allocine_"+type ,result);
});
if type is "movie", result contain a movie object, but if type is "tvseries", result contain a tvseries object. So I need to take the variable "originalTitle" in "tvseries" or "movie" object, so I need to make this :
result.<type>.originalTitle
But, how to use the contain of "type" for this ?
I have try with the javascript method, and the use of "window['type']", but it's don't work in nodeJs .
as javascript objects elements can be accessed as an associative array ( cf mozilla js doc )
using myobject.myproperties is strictly equal to use myobject["myproperties"]
so if a var hold the properties name to read var myvar = "myproperties"; you could also use myobject[myvar]
so, concretely :
var o = {
tvseries : {
originalTitle : "hello world"
}
}, type = "tvseries";
console.log( o[type].originalTitle );
jsfiddle
also, if the result object get only one sub object, named by the type, you can get type name directly from it
var type = Object.keys( myobject )[0];
jsfiddle
or more simply :
var theTitle = myobject[ Object.keys( myobject )[0] ].originalTitle;
jsfiddle
var results = {};
results.a = {originalTitle: "One"};
var results2 = {b:{originalTitle: "Two"}};
console.log(results['a'].originalTitle); //now one
console.log(results2['b'].originalTitle); //now Two
With two ways of creating the object.
Try the fiddle:
http://jsfiddle.net/rmoskal/6rf0juq6/
I have read this (http://www.albahari.com/nutshell/predicatebuilder.aspx)
Here is my code :
var predicateOuter = PredicateBuilder.True<T_Users>();
predicateOuter.And(d => d.code== 357);
var count=tService.GetCount(predicateOuter.Expand());
my service in code first:
public int GetCountSearch(Expression<Func<T, bool>> exp)
{
return _entities.Count(exp);
}
all record in T_Users: 6548
all record where code==357 : 26
But it always returns all records. but why ?
You need to use the results of Add:
// Assign result here to predicateOuter -
predicateOuter = predicateOuter.And(d => d.code== 357);
// This should now function properly
var count = tService.GetCount(predicateOuter.Expand());
Add doesn't modify the predicate, but rather returns a new one with the additional criteria.