Extract specific object contain specific string using Underscore.js

Question

I have this field, and I am using underscore js

I'm trying to access the _id field if it contain .tgz

<html> 
    <head> 
        <title>_.contains() function</title> 
        <script type="text/javascript" src= 
        "https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.9.1/underscore-min.js" > 
        </script> 
        <script type="text/javascript" src= 
        "https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.9.1/underscore.js"> 
        </script> 
    </head>        
    <body> 
        <script type="text/javascript"> 
            var people = [ 
                {"id_": "sakshi.tgz"}, 
                {"id_": "aishwarya.zip"}, 
                {"id_": "ajay.tgz"}, 
                {"id_": "akansha.yml"}, 
                {"id_": "preeti.json"} 
            ] 
         console.log(_.where(people, {id_: "sakshi.tgz"})); 
        </script> 
    </body>  
</html>

I only know how to do the exact match.

console.log(_.where(people, {id_: "sakshi.tgz"}));

Expected Result

As you can see, I'm trying to get 2 of them that end with .tgz.

Any hints for me ?

Fiddle : https://codepen.io/sn4ke3ye/pen/KKzzzLj?editors=1002

Julian Gonggrijp · Accepted Answer · 2020-08-14 23:14:39Z

1

If you have a string, and you want to know whether its last four characters are equal to '.tgz', this is one possible way to do it (MDN: slice):

aString.slice(-4) === '.tgz' // true or false

If that string is the id_ property of some object, just reference the id_ property first and then call slice on it:

someObject.id_.slice(-4) === '.tgz' // true or false

This is something we want to do with every object in a collection, so it is our iteratee. In order to have it applied repeatedly, we wrap it into a function:

function idEndsWithTgz(obj) {
    return obj.id_.slice(-4) === '.tgz';
}

Now we can use this iteratee with _.filter:

console.log(_.filter(people, idEndsWithTgz));

For a more thorough introduction to Underscore, you can also refer to another recent answer of mine: https://stackoverflow.com/a/63088916/1166087

answered Aug 14, 2020 at 23:14

Julian Gonggrijp

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Jan Schultke · Accepted Answer · 2020-08-18 07:07:13Z

1

let newArr = people.filter(obj => obj._id.substr(obj._id.length -4) === ".tgz");

I use filter and substr JavaScript built-in methods of sorting the _id that ends with .tgz.

edited Aug 18, 2020 at 7:07

Jan Schultke

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answered Aug 18, 2020 at 6:14

Zulqarnain Zulqarnain

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