How come my object is iterating from last to first in the for loop?

Question

How come my object is iterating from last to first in the for loop?

I need help understanding arrays.

Here is my data:

And here is my for loop:

 for (var data in statInfo["segment"][0]) {
       console.log(data)
 }

After running the code, I got this result:

The printed data is:

segment5 segment4 segment3 segment2 segment1

Thank you

javascript arrays

Answer 1

Answer №1

The order of object property enumeration is not alphabetical.

Implementations are left to decide the order, as discussed here.

Most browsers tend to follow the order in which properties were created.

If you require specific ordering, consider using an Array, Map, or Set.

With ES2015, you have the option to make an object iterable by defining a custom iteration function that can specify the order of enumeration needed.

var obj = { 
    foo: '1', 
    bar: '2',
    bam: '3',
    bat: '4',
};

obj[Symbol.iterator] = iter.bind(null, obj);

function* iter(o) {
    var keys = Object.keys(o);
    for (var i=0; i<keys.length; i++) {
        yield o[keys[i]];
    }
}

for(var v of obj) { console.log(v); } // '1', '2', '3', '4'

Answer 2

The order of object property enumeration is not alphabetical.

Implementations are left to decide the order, as discussed here.

Most browsers tend to follow the order in which properties were created.

If you require specific ordering, consider using an Array, Map, or Set.

With ES2015, you have the option to make an object iterable by defining a custom iteration function that can specify the order of enumeration needed.

var obj = { 
    foo: '1', 
    bar: '2',
    bam: '3',
    bat: '4',
};

obj[Symbol.iterator] = iter.bind(null, obj);

function* iter(o) {
    var keys = Object.keys(o);
    for (var i=0; i<keys.length; i++) {
        yield o[keys[i]];
    }
}

for(var v of obj) { console.log(v); } // '1', '2', '3', '4'

How come my object is iterating from last to first in the for loop?

Answer №1

Similar questions

Why is my MySQL query not returning the most recent results when using setInterval()?

The statusText variable for getXMLHTTP object is not found when the status is not equal to

Transmitting C# data to a JavaScript script through JSON serialization. Issue encountered: Character invalid

Is there a problem with Angular2 using TypeScript?

Is there a way to implement JavaScript within my Blazor server razor page to modify the styling of a blazor bootstrap button after a form submission?

Choose specific dates from the data pickers based on the membership tiers and level of importance

Unable to display label in form for Angular 2/4 FormControl within a FormGroup

Tips for establishing a connection to a proxy server and executing an http.request through the proxy using nodejs

The Field Projection operation is not taking into account the batchSize field name

Troubleshooting a scope problem with ng-include while maintaining the original template

Add more functionality to the server.js script

Why isn't my SCO considered complete?

It appears that the validation and onChange event handler in Material-UI's TextField are not functioning as anticipated

Vue component encounters issue with exporting JavaScript functions

How can I display a Skeleton when pressing pagination buttons and then turn it off after 3 seconds?

Combining my CSS and JS files is causing code issues (works on my Mac, but not on the server)

How can I retrieve an array from the server side using AngularJS?

Livereload.js is failing to load due to an invalid address

Track and monitor data modifications in Vue.js

Is there a way to automatically collapse all the collapsible elements within the accordion when closing it?