How to automate this code snippet?

snippet.js

var $i = 1;
idea.keywords.forEach(function ( keyword ) {
    if ( $i < idea.keywords.length ) {
        this.keywords += keyword.text + ", ";
    } else {
        this.keywords += keyword.text + ".";
    }
    $i++;
});

//Repetindo o trecho de código, pois não achei uma forma de automatizá-lo.
var $i = 1;
idea.concepts.forEach(function ( concept ) {
    if ( $i < idea.concepts.length ) {
        this.concepts += concept.text + ", ";
    } else {
        this.concepts += concept.text + ".";
    }
    $i++;
});

solution.js

//YEAAAAH! I FOUND IT!

function showMetaFields ( meta_fields ) {
    var $i = 1;
    var content = "";
    meta_fields.forEach(function ( meta_field ) {
        if ( $i < meta_fields.length ) {
            content += meta_field.text + ", ";
        } else {
            content += meta_field.text + ".";
        }
        $i++;
    });

    return content;
}

showMetaFields( idea.keywords );
showMetaFields( idea.concepts );