I worked on pretty good number of functions like given below
function a(declara,callback) {
x = declara.x;
y = declara.y;
return callback.call(this,[declara]);
}
a({x:1,y:2},function(){ console.log(x+" , "+y); });
but I found thats not actually what callback does, could you please explain me, how can a piping structure be implemented as follows:
a({x:1,y:2}).print()
(Something similar to what jQuery does, also kindly explain me the same!)
If I have understood your question correctly, then
function a(declara) {
x = declara.x;
y = declara.y;
return {print:function(){ console.log(x+" , "+y); }}; //return an object whose one key-value has function inside of it.
}
a({x:1,y:2}).print();
Related
PS: I have already searched the forums and have seen the relevant posts for this wherein the same post exists but I am not able to resolve my issue with those solutions.
I have 2 json objects
var json1 = [{uid:"111", addrs:"abc", tab:"tab1"},{uid:"222", addrs:"def", tab:"tab2"}];
var json2 = [{id:"tab1"},{id:"new"}];
I want to compare both these and check if the id element in json2 is present in json1 by comparing to its tab key. If not then set some boolean to false. ie by comparing id:"tab1" in json2 to tab:"tab1 in json1 .
I tried using below solutions as suggested by various posts:
var o1 = json1;
var o2 = json2;
var set= false;
for (var p in o1) {
if (o1.hasOwnProperty(p)) {
if (o1[p].tab!== o2[p].id) {
set= true;
}
}
}
for (var p in o2) {
if (o2.hasOwnProperty(p)) {
if (o1[p].tab!== o2[p].id) {
set= true;
}
}
}
Also tried with underscore as:
_.each(json1, function(one) {
_.each(json2, function(two) {
if (one.tab!== two.id) {
set= true;
}
});
});
Both of them fail for some test case or other.
Can anyone tell any other better method or outline the issues above.
Don't call them JSON because they are JavaScript arrays. Read What is JSON.
To solve the problem, you may loop over second array and then in the iteration check if none of the objects in the first array matched the criteria. If so, set the result to true.
const obj1 = [{uid:"111", addrs:"abc", tab:"tab1"},{uid:"222",addrs:"def", tab:"tab2"}];
const obj2 = [{id:"tab1"},{id:"new"}];
let result = false;
for (let {id} of obj2) {
if (!obj1.some(i => i.tab === id)) {
result = true;
break;
}
}
console.log(result);
Unfortunately, searching the forums and reading the relevant posts is not going to replace THINKING. Step away from your computer, and write down, on a piece of paper, exactly what the problem is and how you plan to solve it. For example:
Calculate for each object in an array whether some object in another array has a tab property whose value is the same as the first object's id property.
There are many ways to do this. The first way involves using array functions like map (corresponding to the "calculate for each" in the question, and some (corresponding to the "some" in the question). To make it easier, and try to avoid confusing ourselves, we'll do it step by step.
function calculateMatch(obj2) {
return obj2.map(doesSomeElementInObj1Match);
}
That's it. Your program is finished. You don't even need to test it, because it's obviously right.
But wait. How are you supposed to know about these array functions like map and some? By reading the documentation. No one help you with that. You have to do it yourself. You have to do it in advance as part of your learning process. You can't do it at the moment you need it, because you won't know what you don't know!
If it's easier for you to understand, and you're just getting started with functions, you may want to write this as
obj2.map(obj1Element => doesSomeElementInObj1Match(obj1Element))
or, if you're still not up to speed on arrow functions, then
obj2.map(function(obj1Element) { return doesSomeElementInObj1Match(obj1Element); })
The only thing left to do is to write doesSomeElementInObj2Match. For testing purposes, we can make one that always returns true:
function doesSomeElementInObj2Match() { return true; }
But eventually we will have to write it. Remember the part of our English description of the problem that's relevant here:
some object in another array has a tab property whose value is the same as the first object's id property.
When working with JS arrays, for "some" we have the some function. So, following the same top-down approach, we are going to write (assuming we know what the ID is):
In the same way as above, we can write this as
function doesSomeElementInObj2Match(id) {
obj2.some(obj2Element => tabFieldMatches(obj2Element, id))
}
or
obj2.some(function(obj2Element) { return tabFieldMatches(obj2Element, id); })
Here, tabFieldMatches is nothing more than checking to make sure obj2Element.tab and id are identical.
We're almost done! but we still have to write hasMatchingTabField. That's quite easy, it turns out:
function hasMatchingTabField(e2, id) { return e2.tab === id; }
In the following, to save space, we will write e1 for obj1Element and e2 for obj2Element, and stick with the arrow functions. This completes our first solution. We have
const tabFieldMatches = (tab, id) { return tab === id; }
const hasMatchingTabField = (obj, id) => obj.some(e => tabFieldMatches(e.tab, id);
const findMatches = obj => obj.some(e => hasMatchingTabField(e1, obj.id));
And we call this using findMatches(obj1).
Old-fashioned array
But perhaps all these maps and somes are a little too much for you at this point. What ever happened to good old-fashioned for-loops? Yes, we can write things this way, and some people might prefer that alternative.
top: for (e1 of obj1) {
for (e2 of (obj2) {
if (e1.id === e2.tab) {
console.log("found match");
break top;
}
}
console.log("didn't find match);
}
But some people are sure to complain about the non-standard use of break here. Or, we might want to end up with an array of boolean parallel to the input array. In that case, we have to be careful about remembering what matched, at what level.
const matched = [];
for (e1 of obj1) {
let match = false;
for (e2 of obj2) {
if (e1.id === e2.tab) match = true;
}
matched.push(match);
}
We can clean this up and optimize it bit, but that's the basic idea. Notice that we have to reset match each time through the loop over the first object.
I have an array that contains dates. and for some reason I can't get it to show on my screen I've been debugging for a few days now and I've tracked it down to a single line, but the line has worked before and I can't figure out what the issue might be.
The array looks like this:
var selectItems =
[ "05-26-2017", "06-02-2017", "06-09-2017",
"06-16-2017", "06-23-2017", "06-30-2017", "07-07-2017", "07-14-2017",
"07-21-2017", "07-28-2017"...];
It's passed as an argument from another function, but that's how it's showing in console.log().
I might be going about this the wrong way, maybe even a lot further around then I need to but this is what I've come up with:
1. function setTHead(selectItems) {
2 var formatString;
3. for (var x = 0; x < 12; x++) {
4. formatString = selectItems[x].replace(/[^0-9/-]/g, "").toString();
5. console.log(selectItems);
6. $('#datTab').append("<div id='col" + x + "' class='column'>'" + formatString + "'</div>");
7. }
8. }
the array up top is what's showing from the console.log 5 lines down.
the sixth line is what is seeming to give me issues. Nothing is put on the page at all.
I'm getting a console error saying:
jQuery.Deferred exception: selectItems is undefined setTHead#http://localhost/mySite/script.js:136:9
startUp2#http://localhost/mySite/script.js:146:5
#http://localhost/mySite/table.php:19:9
mightThrow#http://localhost/mySite/lib/jquery.js:3586:52
resolve/</process<#http://localhost/mySite/lib/jquery.js:3654:49
setTimeout handler*resolve/<#http://localhost/mySite/lib/jquery.js:3692:37
fire#http://localhost/mySite/lib/jquery.js:3320:30
fireWith#http://localhost/mySite/lib/jquery.js:3450:29
fire#http://localhost/mySite/lib/jquery.js:3458:21
fire#http://localhost/mySite/lib/jquery.js:3320:30
fireWith#http://localhost/mySite/lib/jquery.js:3450:29
ready#http://localhost/mySite/lib/jquery.js:3923:13
completed#http://localhost/mySite/lib/jquery.js:3933:9
EventListener.handleEvent*#http://localhost/mySite/lib/jquery.js:3949:9
#http://localhost/mySite/lib/jquery.js:39:9
#http://localhost/mySite/lib/jquery.js:17:3
undefined
followed by:
TypeError: selectItems is undefined
and thats pointing to line 6.
if anyone has any advice I would be very much appreciative. Thank you in advance.
EDIT: A little more code:
function startTblView(defSel) {
if (defSel === true) {
setCookie('defSel', true, 7);
} else{
setCookie('defSel', false, 7);
}
saveSelected();
window.open('table.php', '_self');
defSel = getCookie('defSel');
if (defSel) {
selectItems = getDefDates();
}else {
selectItems = reGetSelected();
}
setTHead(selectItems);
}
defSel, is a boolean passed from my last page stating whether I'm doing a default view or a custom view, the custom view is passed from saveSelected();
saveSelected is a function for just saving the selected global value as a cookie so I can pull it out on the next page.
getDefDates pulls the default values for the array
reGetSelected, gets the selected array from the cookie.
I apologize for wonky naming conventions. I'm the only one working on this site and I'm just making sure the names don't overlap.
You can do this :
HTML code
<div id="datTab"></div>
JS code
var selectItems =
[ "05-26-2017", "06-02-2017", "06-09-2017",
"06-16-2017", "06-23-2017", "06-30-2017", "07-07-2017", "07-14-2017",
"07-21-2017", "07-28-2017"];
function setTHead(selectItems) {
var formatString;
$.each( selectItems, function( index, value ){
formatString = value.replace(/[^0-9/-]/g, "").toString();
$('#datTab').append("<div id='col" + index + "' class='column'>'" + value + "'</div>");
});
};
You can use $.each, its better than 'for' with javascript.
The .each() method is designed to make DOM looping constructs concise
and less error-prone. When called it iterates over the DOM elements
that are part of the jQuery object. Each time the callback runs, it is
passed the current loop iteration, beginning from 0. More importantly,
the callback is fired in the context of the current DOM element, so
the keyword this refers to the element.
I did a JsFiddle
Here.
Background
We have much of our data formatted like
var X = {value:'some val',error:'maybe an error',valid:true}
as a result we find ourselves calling X.value ALL the time.
We don't use the .error or .valid nearly as much, but we do use it.
What I want
To quit calling .value everywhere, but to still have access to meta data on a per data point level.
The Question
Is there one of
A) A way to put meta data on a primitive? attaching .error to an int for example? Is it possible for bools or strings?
B) A way to make a class that can be treated as a primitive, providing a specific data member when I do? IE X.value = 5, X+3 returns 8.
C) A better design for our data? Did we just lay this out wrong somehow?
You can set the method toString() to your object and return value.
var X = {
value: 1,
error:'maybe an error',
valid:true,
toString: function() {
return this.value;
}
}
X.value = 5;
console.log(X+3);
You can represent you data as a function object that also has properties:
var X = () => 1;
X.value = 1;
X.error = 'maybe an error';
X.valid = true,
console.log(X()); // 1
console.log(X.valid); // true
For better design you can encapsulate the creation of the data object in another function.
I'm having trouble chaining ".data" to a raphael.js element.
When I try to retrieve the data later, I get "undefined".
Here's my fiddle: http://jsfiddle.net/HkNgT/9/
//Draw:
paper.circle(circleCenterX, circleCenterY, circleCenterRadius)
.attr({'fill':'blue', 'stroke':'red', 'stroke-width':2, 'opacity': 0.8})
.data({"circleCenterX":circleCenterX,
"circleCenterY":circleCenterY,
"boxYPosition":boxYPosition,
"boxXPosition":boxXPosition})
.id = name+"-circle";
//Output:
console.log("data is = ", paper.getById(name+"-circle").data("circleCenterX"));
With this code, the ".data(...)" part just doesn't work.
When I try to retrieve it (with paper.getById), it displays "data is = undefined".
Other ways that I have tried:
//Doesn't work
paper.circle....
.data("circleCenterX",circleCenterX)
.data("circleCenterY",circleCenterY)
.data("boxYPosition",boxYPosition)
.data("boxXPosition",boxXPosition);
And another:
//Doesn't work
var c = paper.circle....;
c.data("circleCenterX",circleCenterX);
c.data("circleCenterY",circleCenterY);
c.data("boxYPosition",boxYPosition);
c.data("boxXPosition",boxXPosition);
And another:
//DOES work, but gives me huge performance losses
paper.circle....;
paper.getById(name+"-circle").data("circleCenterX",circleCenterX);
paper.getById(name+"-circle").data("circleCenterY",circleCenterY);
paper.getById(name+"-circle").data("boxYPosition",boxYPosition);
paper.getById(name+"-circle").data("boxXPosition",boxXPosition);
Any help?
So, just trying to help, I've never used raphael before. I assume you're trying to retrieve the circleCenterX value?
Inspecting the data function, it looks as though it's only used for setting the value. (It only returns a value, if you're setting a value).
function (b,c){
var d = bb[this.id] = bb[this.id] || {};
if(arguments.length==1){
if(a.is(b,"object")){
for(var e in b)b[g](e)&&this.data(e,b[e]);
return this
}
eve("raphael.data.get."+this.id,this,d[b],b);
return d[b]
}
d[b]=c,eve("raphael.data.set."+this.id,this,c,b);
return this
}
(Afaict, eve is an Event framework, bundled with Raphael. Anyone know where the data goes from here?)
So this isn't going to help.
Inspecting the circle object, I was able to see/pull out a cx value, which I assume is the circleCenterX value that you're looking for...
var circ = paper.getById(name+"-circle");
console.log("baseVal is = ", circ[0].cx.baseVal.value);
console.log("animVal is = ", circ[0].cx.animVal.value);
Gives
baseVal is = 100
animVal is = 100
Is this what you're looking for?
I have a lot of images that are individually updating a drop down selection box. I've been using the following: (changing the replaceContent(number) and a different selectIndex = (number) inside a separate function for each image).
function replaceContent9() {
document.getElementById("ecwid-productoption-8840317-Backgrounds")
.selectedIndex = 0 ; }
I call the function like this:
javascript:replaceContent9
How would I do this with an array so that I might have just one function that is used for all the images. So far not so good at figuring out arrays. Maybe someone could point me in the right direction or suggest a code to try.
I'd go with a hash/lookup object:
var replaceContent = (function() {
var info = {
0: 'ecwid-productoption-8840317-Backgrounds',
1: 'foobar-product',
9: 'whhooott rage'
};
return function( which ) {
document.getElementById( info[ which ] ).selectedIndex = 0 ;
};
}());
This object in its current form pretty much looks like a javascript array because of indexed key names, but for a more general use you should do it like this.
Now you can just call that function like
replaceContent( 9 );