Friday. Last class Some of what we covered: for loop nested for loops toast. The place from which you call a function affects what it can do!

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1 cs1251 Page 1 Friday Tuesday, February 18, :57 PM Last class Some of what we covered: for loop nested for loops toast The place from which you call a function affects what it can do! Classes: Certain types of objects keep popping up over and over again-- it's nice to know when we can expect object to contain similar properties... this is captured by the idea of "class". For example, all the objects in the 'entries' array used to create a menu items have the same properties, so we can think of them as belonging to the same class. When Google pops up an explanation about an object's method it usually shows the class of the object returned by the method: So... things may seem a bit overwhelming right now, but this idea of class gives us a way to organize our thoughts AND to know something about the properties and methods of a large number of objects. Here are the mains classes that we are going to care about: SpreadsheetApp (an object AND a class-- the object that controls interaction with the spreadsheet system) Spreadsheet: A collection of sheets-- this is the class that controls the menu Sheet: The individual spreadsheets (as indicated by the tabs on the bottom) Range: A collection of cells Here's a list of everything you can do with a Spreadsheet object: And a sheet object: And a range object: Let's see if we can SET a cell's value: function setcellvalue(row, col, newvalue){ var sheet=spreadsheetapp.getactivesheet(); // Assign current sheet to variable var cell = sheet.getdatarange().getcell(row,col); // Get cell from those defined

2 cs1251 Page 2 var oldvalue = cell.getvalue(); // Get the value from that cell cell.setvalue(newvalue); return(oldvalue); That's what happens when you call a function that tries to set another cell's value from WITHIN a cell's formula. There is another issue. The spreadsheet shows a LOT of cells, but most of them are actually undefined. There is a rectangle of cells (a range) Notice that this function returns an error if we try to read a cell outside the "data range": More about ranges: A range is a collection of cells. It is perfectly possible for a range of cells to be empty, or to contain only one cell. (In fact, there is no 'cell' class) Here are some methods that we can use to access various ranges method object class notes.getdatarange().getactiverange().getactivecell().getrange(with params) sheet&spreadsheet (uses active sheet) sheet & spreadsheet & spreadsheetapp sheet & spreadsheet sheet&(sort of) spreadsheet The rectangle containing all cells with data The currently selected range of cells The currently active cell (recall a single cell is still a range) The javascript equivalent of selecting a range of cells (comes in various forms-- more on that below).getcell(row, col) range (only) access an individual cell in a range-- this is useful because the row and col are relative to the range! So (1,1) is the first cell in that range..getrangebyname(name) spreadsheet (only) Review naming a datarange from lecture [find that num for them].getdatarange() [show example of going outside the range]

3 cs1251 Page 3.getActiveRange() We used this in the Marvin Snodgrass example. Let's combine this with toast and make certain we understand how it works (Note: toast is a method of a sheet-- and we want that to be the currently selected sheet): function getcurrentselection(){ var sheet = SpreadsheetApp.getActiveSpreadsheet(); var range=spreadsheetapp.getactiverange(); // we could have also used var range=sheet.getactiverange() sheet.toast("current selection is "+range.geta1notation()); Let's do another example, but this time add let's add the entries in the first column of our selection: function numberrows(){ var sheet = SpreadsheetApp.getActiveSpreadsheet(); var range=spreadsheetapp.getactiverange(); sheet.toast("current selection is "+range.geta1notation()); for(var row=1; row<=range.getnumrows();row=row+1){ var cell = range.getcell(row,1); cell.setvalue(row); Let's try to combine together a few different ideas. Create your own spreadsheet, create a custom script for that spreadsheet (be sure to use the create script for spreadsheet so you don't have to copy and paste the onopen() trigger. Now create a function that numbers the entries in the first column, makes those cells bold, and gives a light grey background "#AAAAAA", and sets the font size to be 14.The methods you will need are.setfontweight("bold").setbackground(color).setfontsize(size) When you are done modify the menu in your spreadsheet so it works from a custom menu. Back to the main narrative Here are the sorts of things you can do (don't try to memorize all these): clear all content/formatting copy sheet to another spreadsheet (remember a spreadsheet may contain multiple sheets) delete/insert columns/rows/sheets get active cell/range/selection/sheet/owner (un)hide columns or rows check permissions add/remove a menu set the active cell/range/selection/sheet get/set column/row widths sort data display info We can even extract information about a cell's formatting. Let's write a function that will find the vertical alignment of the data in a cell: function getcellvalignment(row,col){ var sheet=spreadsheetapp.getactivesheet(); return(sheet.getdatarange().getcell(row,col).getverticalalignment(

4 cs1251 Page 4 )); WARNING: the function remembers the return-value of the function until you close and open the browser (I don't make the rules-- I just report them!). This is where SpreadsheetApp.flush() comers in. Bummer! So what's the moral of the story? A javascript function called from a spreadsheet cell can NOT change anything! And even the values it reports might be STUCK in the last value observed! So what good is it? Well, under certain circumstances it CAN change things! It also lets us do logic that is more complicated than what the spreadsheet can handle. To do this, we're going to have to learn about more complicated control structures... The "for... in" construction: function addpropertyaftercreation(){ employee={ first : "Peter", last: "Dolan", age: 41, isprof: true employee.middle="christopher"; // Done here for(property in employee){ Logger.log(employee[property]); Notice the structure: for(<variable> in <object>){ <block of code> This will iterate through every property in an object <block of code> is run once for each property in an object There is NO guarantee about the order in which the properties will be visited What is the value of 'm'? function howmanytimes(){ employee={ first : "Peter", last: "Dolan", age: 41, isprof: true employee.middle="christopher"; // Done here var m = 0; for(property in employee){ Logger.log(employee[property]); m=m+1; Logger.log(m); The empty object: We can create an empty object using { Example: var myobj = {; Since objects can hold *anything* and you can add to them at will, this can be useful! Removing a property from an object:

5 cs1251 Page 5 This uses a command called 'delete'. This webpage: has an awesome explanation that explains *everything*... but it's too much for you right now. If you find yourself using javascript alot come back in a year and look it over... for now, only use delete to remove a property from an object and you'll be fine: function removing(){ var employee={ first : "Peter", last: "Dolan", age: 41, isprof: true ; employee.middle="christopher"; // Added middle here delete(employee.first); // removed first here for(property in employee){ Logger.log(property + " is " + employee[property]); Classes: Certain types of objects keep popping up over and over again-- it's nice to know when we can expect object to contain similar properties... this is done by "class" Look at the helpful popup given by Google. Methods (functions stored in the object) often return objects. The value after the colon is the "class" of the object returned by the method: Some Examples: Spreadsheet, Sheet, Range Every object of class 'Spreadsheet' Array: [ <property>, <property>,..., <property>] Or... with returns [ <property>, <property>, <property>,... ] Arrays are actually objects but there are a few things worth noting: Instead of strings, the properties are numbers The counting starts at 0 (it's a computer science thing!) You will use bracket notation most of the time (maybe always) They have a few other differences that won't matter to most of us. Conceptually arrays are lists (at least for the moment) of stuff. In javascript that stuff can be anything. Accessing values in arrays: Remember that the array starts at 0: function myarray(entry){ {first:"peter",last:"dolan"]; return(arr[entry]); We get an error on the spreadsheet side when we try =myarray(4) This is because google spreadsheets doesn't know how to deal with a java script object. This will work (although it's silly): function myarray2(entry){

6 cs1251 Page 6 {first:"peter",last:"dolan"]; return(arr[entry].last); The "for...in" construction and arrays the for(<var> in <obj>){<stuff> construction works for arrays too... HOWEVER there is NO guarantee that the array entries will be encountered in order function myarray3(){ {first:"peter",last:"dolan"]; for(property in arr){ Logger.log(property + " is " + arr[property]); Logger.log(arr[4]); //Show them how logger deals with objs A better way is this: function myarray4(){ {first:"peter",last:"dolan"]; var i; for(i=0;i<arr.length;i=i+1){ Logger.log(arr[i]); Notice the new type of for construction: for(<initialization>; <condition>; <changer>){ <block of code> Empty arrays: var emptyarr= []; multidimensional arrays (sort of) Since arrays can contain anything... they can also contain OTHER arrays This is SUPER powerful and gives you the ability to store tables of data (and even more complicated structures if you're perverse enough): var matrix = [ [0,1,2], [3,4,5], [6,7,8] ]; matrix[2][1] // the value is 7 Show LOTS of examples Arrays have more methods than general objects. You can find out how many elements are in an array using the '.length' property: WARNING! I AM NOT QUITE TELLING THE TRUTH, BUT THE DETAILS WOULD BE MORE CONFUSING THAN HELPFUL-- IF YOU DON'T DO ANYTHING WEIRD WITH ARRAYS THEN WHAT I HAVE SAID IS TRUE... OTHERWISE IT MAY BE WRONG Add a new element to the end of an array using the.push() method do NOT use delete to remove an element from an array-- it will leave a hole use.splice(<start>,<entries>) to remove elements (warning! Could be slow for big arrays) Some special arrays: Ranges from the spreadsheet show up as ONE argument-- but it's an array:

7 cs1251 Page 7 /* This function expects to be passed a range of cells */ function arrayargument(arr){ var mysum=0; for(var i= 0; i<arr.length;i=i+1){ for(var j = 0; j<arr[i].length;j=j+1){ mysum=mysum+arr[i][j]; return(mysum); The only problem is that the function will FAIL if we pass it just ONE entry /* This function is smarter*/ function mysum(arr){ if(typeof(arr)!="object"){return(arr); // SAFE var mysum=0; for(var i= 0; i<arr.length;i=i+1){ for(var j = 0; j<arr[i].length;j=j+1){ mysum=mysum+arr[i][j]; return(mysum);