Basics
For controlling "cellpadding" in CSS, you can simply use padding
on table cells. E.g. for 10px of "cellpadding":
td {
padding: 10px;
}
For "cellspacing", you can apply the border-spacing
CSS property to your table. E.g. for 10px of "cellspacing":
table {
border-spacing: 10px;
border-collapse: separate;
}
This property will even allow separate horizontal and vertical spacing, something you couldn't do with old-school "cellspacing".
Issues in IE ≤ 7
This will work in almost all popular browsers except for Internet Explorer up through Internet Explorer 7, where you're almost out of luck. I say "almost" because these browsers still support the border-collapse
property, which merges the borders of adjoining table cells. If you're trying to eliminate cellspacing (that is, cellspacing="0"
) then border-collapse:collapse
should have the same effect: no space between table cells. This support is buggy, though, as it does not override an existing cellspacing
HTML attribute on the table element.
In short: for non-Internet Explorer 5-7 browsers, border-spacing
handles you. For Internet Explorer, if your situation is just right (you want 0 cellspacing and your table doesn't have it defined already), you can use border-collapse:collapse
.
table {
border-spacing: 0;
border-collapse: collapse;
}
Note: For a great overview of CSS properties that one can apply to tables and for which browsers, see this fantastic Quirksmode page.
Well, the problem is that the variable i
, within each of your anonymous functions, is bound to the same variable outside of the function.
ES6 solution: let
ECMAScript 6 (ES6) introduces new let
and const
keywords that are scoped differently than var
-based variables. For example, in a loop with a let
-based index, each iteration through the loop will have a new variable i
with loop scope, so your code would work as you expect. There are many resources, but I'd recommend 2ality's block-scoping post as a great source of information.
for (let i = 0; i < 3; i++) {
funcs[i] = function() {
console.log("My value: " + i);
};
}
Beware, though, that IE9-IE11 and Edge prior to Edge 14 support let
but get the above wrong (they don't create a new i
each time, so all the functions above would log 3 like they would if we used var
). Edge 14 finally gets it right.
ES5.1 solution: forEach
With the relatively widespread availability of the Array.prototype.forEach
function (in 2015), it's worth noting that in those situations involving iteration primarily over an array of values, .forEach()
provides a clean, natural way to get a distinct closure for every iteration. That is, assuming you've got some sort of array containing values (DOM references, objects, whatever), and the problem arises of setting up callbacks specific to each element, you can do this:
var someArray = [ /* whatever */ ];
// ...
someArray.forEach(function(arrayElement) {
// ... code code code for this one element
someAsynchronousFunction(arrayElement, function() {
arrayElement.doSomething();
});
});
The idea is that each invocation of the callback function used with the .forEach
loop will be its own closure. The parameter passed in to that handler is the array element specific to that particular step of the iteration. If it's used in an asynchronous callback, it won't collide with any of the other callbacks established at other steps of the iteration.
If you happen to be working in jQuery, the $.each()
function gives you a similar capability.
Classic solution: Closures
What you want to do is bind the variable within each function to a separate, unchanging value outside of the function:
var funcs = [];
function createfunc(i) {
return function() {
console.log("My value: " + i);
};
}
for (var i = 0; i < 3; i++) {
funcs[i] = createfunc(i);
}
for (var j = 0; j < 3; j++) {
// and now let's run each one to see
funcs[j]();
}
Since there is no block scope in JavaScript - only function scope - by wrapping the function creation in a new function, you ensure that the value of "i" remains as you intended.
Best Answer
There's a CSS function called calc that is starting to get pretty good support. The syntax works as followed:
(Note that the whitespace around the operators is significant)
This allows true dynamic computational support in CSS. With a preprocessor, you can only combine static lengths with static lengths, and relative lengths with relative ones.
At this point in time calc has achieved widespread support and should be safe to use unless you have specific needs for supporting legacy browsers.