javascript eval - how to assign value to object property?

Question

Possible Duplicate:
Dynamic object property name

I have an object like this

var localAppConfig = {
    wallet:0,
    paySomeone:0,
    payBills:0,
    accounts:0,
    moveMoney:0,
    alerts:0,
    offers:0,
    checkIn:0
};

I want to set value 1 for particular elements within this localAppConfig

Which element needs to be set is retrieved from the json - which arrives from the server.

say, I want to set value = 1 for wallet, paySomeone, payBills, alerts, offers, checkIn

These are retirved from the json like

for(var i=0;i<len;i++){
        var name = list[i].handle;
        var accessor = eval('localAppConfig.'+name);
        eval('localAppConfig.'+name)=1;
    }

var name contains name of the element and I am able to access its value correctly,

How can I set the value using javascript?

I tried accessor=1 but its not working.

Thanks :)

_EVIL_ roams the world: "When all you have is the eval hammer, everything looks like your thumb" — Elias Van Ootegem, Aug 08 '12 at 15:22
@AdityaParab: I don't hate anybody, and I don't hate `eval`, I hate the way `eval` is abused by many: the only time `eval` is acceptable is to support `JSON` in older browsers. (ps: I din't down-vote) — Elias Van Ootegem, Aug 09 '12 at 07:33
@EliasVanOotegem : Its ok :) ... I didn't know the other syntax to access object property the time I posted this.. Thanks for you help :) — AdityaParab, Aug 10 '12 at 07:59

score 3 · Answer 1 · answered Aug 08 '12 at 15:21

3

You should do this instead:

var accessor = localAppConfig[name];
localAppConfig[name] = 1;

answered Aug 08 '12 at 15:21

James M

18,506
3
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score 3 · Accepted Answer · answered Aug 08 '12 at 15:23

Anyhow: try this on for size:

localAppConfig[name] = 1;//where name is a variable of choice, it's value will be used as the propertyname

And again:

-When all you have is the eval hammer, everything looks like your thumb. –Brendan Eich in response to: we should encourage use of eval() rather than the Function constructor for dynamic creation of functions.

But why use a list of the properties? you might as well use a for...in loop: in case of objects, like yours, it's perfectly all right.
As long as you check .hasOwnProperty, too:

for (var prop in localAppConfig)
{
    if (localAppConfig.hasOwnProperty(name))
    {
        //set, delete... do whatever
    }
}

score 1 · Answer 3 · answered Aug 08 '12 at 15:23

1

Try localAppConfig[name] = 1;

It's just a javascript object, no need to use eval() on it.

answered Aug 08 '12 at 15:23

A Person

1,350
12
23

score 0 · Answer 4 · answered Aug 08 '12 at 15:21

Don't use eval(). You can add a property by referencing the index of that value within your object. If it doesn't exist then it will be created, otherwise the value will be overridden.

Try the following instead:

// localAppConfig[list[i].handle] = 1; 

for(var i=0;i<len;i++){         
    localAppConfig[list[i].handle] = 1;
}

Or if you intend to reference the variable in another place then set a variable with the value of list[i].handle:

for(var i=0;i<len;i++){
    var name = list[i].handle;        
    var accessor = localAppConfig[name];    
    localAppConfig[name] = 1;
}

javascript eval - how to assign value to object property?

4 Answers4