github source

What does it do

Calculate how many lines are there when you put a long string into a div/span that has a width.

Getting Started

First, let’s set it up. We create a div with id para. We limit it to 68px so we can see the effects of the word break.

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Getting the width of a string involves first putting test text into your div #para. Then,

1) We need to the get element object of #para first. It will contain all the information you need about this element object. We will be using it in the next step to get font and font size info.

2) By using the global window object, we use getComputedStyle of an element object to get style information such as font-size, font-family, background-color…etc.
We do this by calling getPropertyValue on the style object that’s returned. We specify which style attribute we want to get by inserting the style name.

3) then the font size

4) Using JQuery, create a span in your DOM.
Using jQuery, insert your text, apply the font and font size, and call width on it.
It will give you the pixel width on it.

The $.fn is an alias for jQuery.prototype which allows you to extend jQuery with your own functions.
We create our own function textWidth. It takes a paragraph, font, and a fontSize. Then it returns you
the width in pixels.

We first check to see if there’s a property placeholderEl. If it doesn’t exist, we attach the property
to our function. We then create a span element object and append it to the document’s body. We attach the
property placeholderEl to that span object.

We then insert the text into the span, and apply the font and font size to the text using css function.
then we call width on the span object to get the pixel.

thus, so far, you should have something like this in your JS file:

Logic

Now that we can get an accurate width of a paragraph with applied font, let’s take a look at how we’re going to tackle the issue.
note: limit means the end of the width.

A) no-space long word past limit

In the first basic situation, the long word will stay as is. This is because the browser do not break a word. It will only break a sentence, when it detects a space, but will never break a word in half.

B) long word past limit, then space

The second situation is that our long word goes past the limit. Then it has a space. In this case, we have two parts.
– The string left of the space.
– The string right of the space.

The right part of the space then gets broken and starts at the next line. The space is the last character of the first line.

C) long word past limit, with a previous space

When we reach the limit, but there was a previous space. Thus, we have two parts again.
– The string left of the space.
– The string right of the space.

The string to the right of the space gets broken and start at line two. The string left of the space, remains at line 1.

D) long word past limit, with previous multiple spaces

Sometimes, there will be multiple spaces previously. So when we hit the limit, how do we break it? The answer is that we find the last space. We don’t care any previous spaces. All we care about is the last space because we need to see how to break the substring that just went past the limit.

Implementation

We’ll do this in es5.

We first create a function to be new-ed later. It will contain the object’s property and data. We need the basic things such as:
– text (string)
– the width function we’re going to use to calculate string widths on the browser (function)
– font (string)
– fontSize (string)

We also pass in the div element’s id so that we can get the width.

Then, let’s implement a function in the prototype so that all instances will use it.

We can easily get the width of the text by using our textWidth function. However, when you use space ‘ ‘, you’ll get 0. So we do a workaround by giving the strings ‘a’. Then a space a, (‘a a’). That way, we know the width of a. And then, can calculate the width of space.

We calculate the width of the string. If the string is a space, then we simply give it the width of space, which we pass in.
However, if not a space, then we calculate it by passing our text, our font, and font size. We then pass the result into a callback to be processed by others.

The Logic

Given a long text, we run through each character.

1) get width of the char
2) append the width onto a total width.

For every add of a width, we check to see if our total text has passed the limit.

Thus,

using our prototype function getCharWidth. Also, notice “holder”. Holder basically holds the added character so far.
Another thing to notice is that there is a bool to check to see if a previous space exist.

The key is to check for situations when we hit past the limit.
If after passing the limit, and we detect a space, then we gotta save the left side of the string.

In order to do this, we use a ‘holder’ string to hold everything. Also, notice we have calculated the width of the space also.

– passed the limit
– no previous space was detected
– current char is a space

Thus, we save the everything that was held up to now. But where do we save it to?

We simply save it into an array that will represent the formatting of our paragraph.
First sentence is array[0], second array[1]…etc.

Thus, in our constructor function:

now..back to our calcNumOfLines.

where

Basically, if we pass the limit, but no space is found, we just save it. This will satisfy A).
As each additional character is processed, and we find that the current processed character is a space (assuming no previous space), then we simply store it.
This resolves B).

else if we’re past the limit and the character is NOT a space, and there was a previous space, then we resolve cases
C) and D)

full source
https://github.com/redmacdev1988/NumberOfLines

ref –
https://github.com/janl/mustache.js/
https://medium.com/@koalamango/javascript-templating-with-mustache-js-b50919cb4f57
https://www.elated.com/articles/easy-html-templates-with-mustache/

Templates are a great way to separate your website’s code from its design.

Mustache is a logic-less template syntax. It can be used for HTML, config files, source code – anything.

It works by expanding tags in a template using values provided in a hash or object

One of Mustache’s big plus points is that is logic-less, which means it keeps your templates very neat and tidy. There are no messy if … then or looping constructs embedded within a Mustache template; it’s all just markup and simple Mustache tags. All the logic is hidden away inside your data objects (and the code that creates or fetches them).

A mustache template is a string that contains any number of mustache tags.

Tags are indicated by the double mustaches that surround them.
{{person}} is a tag, as is {{#person}}

Using mustache basics

• First, we’ll include mustache js file
• Second, we’ll create a template with tags
• Then, we’ll use a object’s values provided by its properties
• Finally, we’ll see the output from the template + object by using Mustache.render

include the mustache js file in your header

Create the template

The template is a string.
For example: “{{name}} is a {{occupation}}”

The tags are:
{{name}}
{{occupation}}

It expands the tags by using object view.
It looks inside this object for properties name and occupation. Then it would expand the tags with the values occupied at properties name, and occupation.

Load the template

Then, simply execute our tags, templates, objects, and render them.
Id person for paragraph p is to hold the result.

Another Example

This time, we introduce the concept of sections.

Sections render blocks of text one or more times, depending on the value of the key in the current context. A section begins with a hashtag and ends with a slash:

template:

The behavior of the section is determined by the value of the key:

object:

Since the object property is true, we display what’s between Robot tags.

My name is Pinocchio!

Your output when you run the web file is:

Hello Pinocchio You live in the woods! Well, you are friends with animals

Inverted Sections

An inverted section begins with a caret (hat) and ends with a slash.

Inverted section means when its false, it displays. When true, it won’t display.

template:

object:

Since Robot is false, let’s display what’s in between the Robot tags because this is an inverted section.

No content!

Another Example

In this next example, we’ll first use textarea to hold strings that can represent our templates and data objects. You can specify the strings in your html code, or simply have the user enter them via the web page.

In html, you can put the contents of the textarea in between textarea tags. Thus, that is the text that will be appear when the textarea tags are rendered on the web page. In our case, we put the template string inside the textarea with id template.

When we’re processing the code, we need to get whatever the input is from the textarea “template”. Thus, we get the string from the textarea via javascript like so:

In, Mustache.Render(template, object), the template parameter needed is a string. Thus, our templateStr can simply be passed in.

The string we pass into the textarea “data” is the object. However, the object must be a code evaluation. In other words, we have to convert the string into code. We can use javascript’s eval function.

Remember that whatever variable you decide to use for the object in dataStr must be used in code.

In our case, it is “hadoken”.

In our js, we basically get the data from the textareas. Then pass them into Mustache.render function. It returns the result that we need.

And we finally throw that result into the html.

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Source Code

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ref – https://stackoverflow.com/questions/1646698/what-is-the-new-keyword-in-javascript
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/new

Prototype and Inheritance in JS (non-class)

Creating a user-defined object requires two steps:

1） Define the object type by writing a function.

2） Create an instance of the object with new.

To define an object type, create a function for the object type that specifies its name and properties. An object can have a property that is itself or another object.

When the code new Foo(…) is executed, the following things happen:

1) A new object is created, inheriting from Foo.prototype.

2) The constructor function Foo is called with the specified arguments, and with this bound to the newly created object. new Foo is equivalent to new Foo(), i.e. if no argument list is specified, Foo is called without arguments.

3) Normally constructors don’t return a value.

If the constructor function doesn’t explicitly return an object, the object created in step 1 is used instead.
However, sometimes, they can choose to do so if they want to override the normal object creation process of using step 1.
If they do return an object in the constructor function, then the object returned by the constructor function becomes the result of the whole new expression. Reference p would then point to this returned object.