Array/Object as index

Question

In a jQuery ajax request, I have error handling that happens with callback:

success: function(a) {
    if (a.error) switch (a.error) {
    case "formError":
    case "clientError":
    case "limitError":
        doErrorCorrection();
        alert("Client-sided error: " + a.errorMessage);
        break;
    case "serverError":
    case "500Error":
        doRollback();
        doTransactions();
        break;
    case "generalError":
        alert("One plus one is: " + (1+1));
    } else doActionsWith(a)
}

I would like to move this into an object of it's own such as:

var errors = {
    ...
    formError: function() {...},
    generalError: function() {...},
    ...
};

With that, I could say:

success: function(a) {
    if (a.error) return errors[a.error](a.errorMessage);
    doActionsWith(a)
}

The issue is that I have tons of reflow from switch, and if I were to translate this to an object, that would mean repetition of the same functions over and over.

var errors = {
    formError: function() { methodA() },
    clientError: function() { methodA() },
    limitError: function() { methodA() },
    ...
    //more if I had more reflows
};

So I thought of having an array/list as the index. I messed around setting an index like:

var arr = {
    test: 'hello world'
};

var index = ['a', 'b', 'c'];

arr[index] = 'array as index';

It worked, but only partially. When I ran the keys through, they returned as a string:

for (var key in arr) console.log(key)
//test
//a,b,c

Running the same test with an object, index = {'a' = true} only set the string index object Object to array as index.

Okay, so an array/object as an index won't work, how should I restructure my switch into an object?

Note that { formError: function() { methodA() } } is the same as { formError: methodA } — JJJ
– JJJ, Commented Aug 26, 2013 at 8:08
I'm not clear with what you're asking... for..in loop worked for you with object keys but not with an object? btw. your second object index = { 'a' = true } is incorrect, should be index = { 'a': true } — Dziad Borowy
– Dziad Borowy, Commented Aug 26, 2013 at 8:10
They did not work in both tests. The keys returned were string literals. It seems the object keys were normalized to a string. — Dave Chen
– Dave Chen, Commented Aug 26, 2013 at 8:11

Mohit Pandey · Accepted Answer · 2013-08-26 08:20:01Z

1

You can maintain an array of objects like that:

var arr = [{ 
    msg: 'Hello World',
    val: ['a', 'b', 'c']
}, {
    msg: 'This is a dummy text.',
    val: ['d', 'e', 'f']
}];

// now perform your search
for (var obj in arr) {
    var idx = arr[obj].val.indexOf('a');
    if (idx !== -1) { // if val is found
        alert(arr[obj].msg);    // alerts "Hello World"
    }
}

answered Aug 26, 2013 at 8:20

Mohit Pandey

3,8597 gold badges28 silver badges38 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Dave Chen Over a year ago

I changed msg to handler and val to handles. +1 & accepted.

Ja͢ck · Accepted Answer · 2013-08-26 08:36:04Z

1

When you use arrays as object property names, they're turned into a string equivalent, so [1,2,3] gets used as "1,2,3"; it won't work like "if value is either of these values".

For your particular problem I would create a dedicated error handler object like this:

function ErrorHandler(map, handlers)
{
    this.map = map;
    this.handlers = handlers;
}

ErrorHandler.prototype.handle = function(a) {
    var handler = this.handlers[this.map[a.error]];

    if (handler) {
        handler(a);
    }
}

The constructor takes an error map and handling functions; when .handle() is called, it will find the handler and run it. This is how you instantiate it:

var myHandler = new ErrorHandler({
    "formError": "clientError",
    "clientError": "clientError",
    "limitError": "clientError",
    "serverError": "serverError",
    "500Error": "serverError"
    "generalError": "genericError"
}, {
    clientError: function(a) {
        doErrorCorrection();
        alert("Client-sided error: " + a.errorMessage);
    },
    serverError: function(a) {
        doRollback();
        doTransactions();
    },
    genericError: function(a) {
        alert("One plus one is: " + (1+1));
    }
});

To use it:

success: function(a) {
    if (a.error) {
        myHandler.handle(a);
    } else doActionsWith(a)
}

edited Aug 26, 2013 at 8:36

answered Aug 26, 2013 at 8:14

Ja͢ck

174k39 gold badges269 silver badges317 bronze badges

3 Comments

Dave Chen Over a year ago

To prevent pollution in the scope, I have designed something like this. The issue would be that I would need to say formError: function() { this.methods.clientError() } which would be too much repetition.

Ja͢ck Over a year ago

@DaveChen Updated answer to highlight another option.

slebetman Over a year ago

To prevent pollution in current scope simply use a closure like this: jsfiddle.net/slebetman/PuKUL . No excessive repetition necessary.

Collectives™ on Stack Overflow

Array/Object as index

2 Answers 2

1 Comment

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related