JavaScript quick assignment

Question

JavaScript quick assignment

I've been exploring method chaining in Javascript, inspired by jQuery. I created a wrapper around an array that can accept coordinate points and transformation methods. The syntax generally looks like this:

myPath = new Path().move({x:50,y:50}).line({x:20,y:20}).rotate(Math.PI/3);

It works well and is more readable than a string of coordinates. Now I want to duplicate the existing path by concatenating its reverse:

// create a symmetrical path.
myPath = new Path().move().line().etc().etc.concat(myPath.reverse());

However, this fails because myPath is unknown as an argument to concat. It works when I do:

var myPath = new Path();
myPath.move().line().etc().etc().concat(myPath.reverse());

I'm wondering if there is a shorter way in Javascript to immediately assign the new object to the variable definition? If not possible in Javascript, I'd like to know if it's achievable in other languages.

Regards, Jeroen.

javascript variable-assignment

Answer 1

Answer №1

Function concat in Path prototype is designed to concatenate paths with a flag indicating concatenation in progress.
Reverse function in the prototype reverses the path array either alongside concatenation or individually.
A new instance of Path, myPath, is created with chained methods for moving, lining, etc., followed by concatenation and reversal.

<p>This approach may not be the most elegant, but it gets the job done.</p>

<blockquote>
  <p>Have you thought about a more concise way to assign the new object to the variable?</p>
</blockquote>

<p>Unfortunately, there isn't a shorter method because you can't reference an object that doesn't exist yet.</p>

<hr>

<p>An alternate way to achieve this:</p>

<pre><code>(myPath = new Path()).move().line().etc().concat(myPath.reverse());

Answer 2

Function concat in Path prototype is designed to concatenate paths with a flag indicating concatenation in progress.
Reverse function in the prototype reverses the path array either alongside concatenation or individually.
A new instance of Path, myPath, is created with chained methods for moving, lining, etc., followed by concatenation and reversal.

<p>This approach may not be the most elegant, but it gets the job done.</p>

<blockquote>
  <p>Have you thought about a more concise way to assign the new object to the variable?</p>
</blockquote>

<p>Unfortunately, there isn't a shorter method because you can't reference an object that doesn't exist yet.</p>

<hr>

<p>An alternate way to achieve this:</p>

<pre><code>(myPath = new Path()).move().line().etc().concat(myPath.reverse());

Answer 3

Answer №2

To create a copy of the current path, you can implement a duplicate function like this:

Path.prototype.duplicate = function () {
    var copiedPath = this.copy().reverse();
    this.combine(copiedPath);
    return this;
}

After defining the duplicate method, you can use it by invoking `var myPath = new Path().move().line().etc().duplicate().

Answer 4

To create a copy of the current path, you can implement a duplicate function like this:

Path.prototype.duplicate = function () {
    var copiedPath = this.copy().reverse();
    this.combine(copiedPath);
    return this;
}

After defining the duplicate method, you can use it by invoking `var myPath = new Path().move().line().etc().duplicate().

JavaScript quick assignment

Answer №1

Answer №2

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