Get the first key name of a JavaScript object

Question

Let s assume we have the following JavaScript object  ahash     quot one quot    1 2 3    quot two quot    4 5 6    Is there a function that returns the first key name for the given object  From the example above I want to get one as a result of that function

User · Answer

Try this   for  var firstKey in ahash  break   alert firstKey        one

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In Javascript you can do the following   Object keys ahash  0

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You can query the content of an object  per its array position For instance    let obj    plainKey   plain value      let firstKey   Object keys obj  0       plainKey   let firstValue   Object values obj  0       plain value       or      let  key  value    Object entries obj  0        plainKey    plain value     console log key       plainKey   console log value       plain value

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There s no such thing as the  first  key in a hash  Javascript calls them objects    They are fundamentally unordered   Do you mean just choose any single key   for  var k in ahash        break       k is a key in ahash

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With Underscore js  you could do     find    one    1 2 3    two    4 5 6       It will return  1 2 3

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If you decide to use Underscore js you better do     values ahash  0    to get value  or     keys ahash  0    to get key

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I use Lodash for defensive coding reasons     In particular  there are cases where I do not know if there will or will not be any properties in the object I m trying to get the key for   A  fully defensive  approach with Lodash would use both keys as well as get   const firstKey     get   keys ahash   0

User · Answer

you can put your elements into an array and hash at the same time    var value    1 2 3   ahash     one   value   array push value     array can be used to get values by their order and hash could be used to get values by their key  just be be carryfull when you remove and add elements

[javascript] Get the first key name of a JavaScript object

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