您如何使用Javascript中的长变量？

Question

How do you recommend to work with long variables in Javascript? Thanks!

For example...

window.location.hash.substring(2).split("/")[0].something().hello;

object["object"].object(object.hello.how.are.you[another.object(function.inisde())]);

My solutions

• Use with() { (...) }

Answer 1

如果要多次使用它，请务必将其分配给另一个变量

var simple = object.hello.how.are.you[another.object(function.inisde())];

Answer 2

I find it useful (in any language) to NOT chain method calls together in most cases. The cons to doing this are

1) If there is some sort of null exception, it is difficult to know where it occurs, especially if the code looks like

if (a.b.c.d.e || f.g.h.i.k) { ... }

then your NPE like exception could have happened in any of 10 places. Imagine if the variables are more than 1 letter long.

2) The code is less readable this way. The following is infinitely more readable.

var b = a.b,
    c = b.c,
    d = c.d,
    e = d.e;
var conditionOne = e.isTrue()

you don't necessarily need to create a var for every level, but you could for levels that make sense.

3) Its easier to see what is going on in a debugger if the variables are separated out.

The bottom line is, with some extra typing your code is a lot more readable and a lot more maintainable.

Answer 3

If you have to use expressions like

object["object"].object(object.hello.how.are.you[another.object(function.inisde())]);

it usually means code is badly designed. :) The usual method to make this code comprehensible is to use variables. It requires more code, but at least it becomes readable.

var anotherObject = another.object(function.inisde())
var hello = object.hello.how.are.you[anotherObject];
object["object"].object(hello);

If the expression is linear, you can easily split it into several lines.

window.location.hash.substring(2)
    .split("/")[0]
    .something().hello;