jmh-assn09-filters.js

/*  File:  D:\H-Drive\public_html\TUES\jmh-assn09-filters.js
 *  Jesse M. Heines, UMass Lowell Computer Science, heines@cs.uml.edu
 *  Copyright (c) 2014 by Jesse M. Heines.  All rights reserved.  May be freely 
 *    copied or excerpted for educational purposes with credit to the author.
 *  updated by JMH on November 28, 2014 at 9:18 AM
 */


"use strict";  // to ensure that all variables are declared before use


// return a substring of the string named in the AngularJS template given
//    the string itself and the staring and ending character numbers
// adapted from http://jsfiddle.net/tUyyx/
myApp.filter("substring", function () {
    /**
     *  @param str   the string selected by the AngularJS template
     *  @param start the index of the character at which to start the substring
     *  @param end   the index of the character at which to end the substring,
     *      but note that this character is *NOT* included in the substring
     */
    return function (str, start, end) {
        // if the first parameter is invalid, return a blank string
        if (typeof (str) === "undefined" || typeof (str) !== "string") {
            return "";
        } else {
            // if the second parameter is missing or invalid, set it to 0
            if (typeof (start) === "undefined" || isNaN(start) || start < 0) {
                start = 0;
            }
            // if the third parameter is missing or invalid, set it to the string length
            if (typeof (end) === "undefined" || isNaN(end) || end > str.length) {
                end = str.length;
            }
            // extract and return the desired substring
            return str.substring(start, end);
        }
    };
});

// given an email address, return the part before the @ sign
myApp.filter("upToAtSign", function () {
    /**
     *  @param str the string selected by the AngularJS template
     */
    return function (str) {
        // if the first parameter is invalid, return a blank string
        if (typeof (str) === "undefined" || typeof (str) !== "string") {
            return "";
        }
        // find the position of the @ sign
        var posAt = str.indexOf("@");
        // if the @ sign is not found, return the original string
        if (posAt === -1) {
            return str;
        } else {
            // otherwise, return the substring up to but not including the @ sign
            return str.substring(0, posAt);
        }
    };
});

// given a string containing HTML tags, return a version of it that displays
//    as true HTML when displayed by the AngularJS template
// see http://creative-punch.net/2014/04/preserve-html-text-output-angularjs/
myApp.filter("unsafe", function ($sce) {
    /**
     *  @param str the string selected by the AngularJS template
     *      note that in the database, a blank comment is represented a null
     *      in the Boolean expression below, since null is false, ! str is true
     */
    return function (str) {
        // if the comment string is not a string (it's null or of type object or an empty 
        //    string), return a note that no comment was entered
        if (typeof (str) !== "string" || str === "") {
            return $sce.trustAsHtml("(<em>no entry</em>)");
        }
        // otherwise, return the comment string in HTML format
        else {
            return $sce.trustAsHtml(str);
        }
    };
});

// add one to the numeric string selected by the AngularJS template
myApp.filter("increment", function () {
    /**
     *  @param num the string selected by the AngularJS template, which should be a number
     *                note that JavaScript reports the type as "number", not "string"
     *  @param inc the increment to add to str
     */
    return function (num, inc) {
        // if the first parameter is invalid, return a blank string
        if (typeof (num) === "undefined" || typeof (num) !== "number") {
            return 0;
        }
        // if the first parameter is not a number, return 0
        else if (typeof (inc) !== "undefined" &&
                (typeof (inc) !== "number" || isNaN(inc))) {
            return 0;
            // else add one to the parameter and return the result
        } else {
            // if the second parameter is missing or invalid, set it 1
            if (typeof (inc) === "undefined") {
                inc = 1;
            }
            // return the incremented number
            return num + inc;
        }
    };
});

// extract only the first and last names of a "LastName, FirstName MiddleName" string
myApp.filter("firstLastOnly", function () {
    /**
     *  @param str the string selected by the AngularJS template
     */
    return function (str) {
        // find position of comma in input string
        var posComma = str.indexOf(",");
        // extract last name part
        var strLastName = str.substring(0, posComma).trim();
        // extract first name part
        var strFirstName = str.substring(posComma + 1).trim();
        // find position of space in first name part
        var posSpace = strFirstName.indexOf(" ");
        // cut off middle name if found
        if (posSpace !== -1) {
            strFirstName = strFirstName.substring(0, posSpace);
        }
        // reconstruct and return the "LastName, FirstName" string
        return strLastName + ", " + strFirstName;
    };
});