Question

195

JavaScript: How can I get all the keys and values of an object that begin with a specific string?

rated 0 times [ 200] [ 5] / answers: 1 / hits: 10996 / 11 Years ago, tue, december 10, 2013, 12:00:00

I am trying to get all the keys and values of an object that begin with imageIds.

My object appears as the following:

{

    title: 'fsdfsd',

    titleZh: 'fsdfsd',

    body: 'fsdf',

    bodyZh: 'sdfsdf',

    imageIds: '/uploads/tmp/image-3.png',

    imageIdsZh: '' 

}

but I only need the properties imageIds, and imageIdsZh. However tomorrow, a object might contain imageIdsBlah and I would need to pick it up as well. I could remove the first few properties from the object, but then the next object might contain additional properties such as foo: 'bar'

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giovanny

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2 Years ago

answered 11 Years ago ira · Accepted Answer

Some functional style awesomeness:

var data = {

    title: 'fsdfsd',

    titleZh: 'fsdfsd',

    body: 'fsdf',

    bodyZh: 'sdfsdf',

    imageIds: '/uploads/tmp/image-3.png',

    imageIdsZh: '' 

};



var z = Object.keys(data).filter(function(k) {

    return k.indexOf('imageIds') == 0;

}).reduce(function(newData, k) {

    newData[k] = data[k];

    return newData;

}, {});



console.log(z);

Demo: http://jsfiddle.net/ngX4m/

Some minor explanation:

We use Array.prototype.filter() function to filter out the keys that start with `imageIds2

We use Array.prototype.reduce() to convert an array of filtered keys into an object of key-value pairs. For that we use the initial value of {} (an empty object), fill it and return from every execution step.

UPD:

A fair update from @GitaarLAB:

Object.keys is ES5, but returns an objects own properties (so no need for obj.hasOwnProperty(key))