JavaScript. Two Dimensional Arrays

Two dimensional arrays are everywhere. For instance, all data coming from a database table would probably find its way to you as a two dimensional array. Here is an example of one:

[ 
    { "id":1, "first_name":"Tinna", "last_name":"Donne", }
    { "id":2, "first_name":"Joanne", "last_name":"Smith", }
]

Working with 2 dimensional arrays in JavaScript is not the nicest of experience. The standard Array functions do not provide anything out of the box to help with.

Here are a few functions, attached to the Array prototype, which can make your life easier, when sorting through two dimensional arrays.

Array.prototype.selectOne = function (where) {

var filtered = this.selectWhere(where);

if (filtered.length > 0) {

     return filtered[0];

  }

 return null;

};

Array.prototype.selectWhere = function (where) {

var columnName = where[0];

var comparator = where[1];

var compareValue = where[2];

var filtered = [];

 for (var i = 0; i < this.length; i++) {

    var row = this[i];

    if (row[columnName] == compareValue) { // Leave as is, do not use "==="

         filtered.push(row);

     }

}

return filtered;

};

Here is an example how to use:

// Get the person with ID=2
var person = people.selectOne(['id','=','2']);

// Get the person with last name Smith
var person = people.selectOne(['last_name','=','Smith']);

// Get all the people whose first name is Joanne
var joannes = people.selectWhere(['last_name','=','Smith']);