JSFiddle - React, Tailwind, and code Playground

JavaScript

var arr = ['orange', 'red', 'black', 'white'];

arr.deleteElem = function ( val ) {
    for ( var i = 0; i < this.length; i++ ) {
        if ( this[i] === val ) {
            this.splice( i, 1 );
            return i;
        }
    }
};

var idx = arr.deleteElem( 'red' );

document.write(
    'Array: ' + arr + '<br>' +
    'Index of removed element: ' + idx
);