Gordon  Taylor

Gordon Taylor

1669470540

How to Code A Random String Generator Program using JavaScript

Code recipe: JavaScript random string generator

There are several ways to generate a random string with JavaScript, depending on the requirements you need to meet.

You can generate both random alphanumeric string, which is a combination of letter and numbers, and you can also generate a letter-only string. This tutorial will help you to learn both.

JavaScript random alphanumeric string

You can generate a random alphanumeric string with JavaScript by first creating a variable that contains all the characters you want to include in the random string.

For example, the following characters variable contains the numbers 0 to 9 and letters A to Z both in upper and lower cases:

const characters =
  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";

Once you settled on the characters you want to include in your random string, you need to determine the length of the random string. For this tutorial, let’s generate a random string with 9 characters :

const characters =
  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
const length = 9;

Now you need to create another variable that contains the random string. Just initialize the variable with an empty string like this:

const characters =
  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
const length = 9;
let randomStr = "";

It’s time to generate the random string. Write a for loop that will iterate as long as the value of length variable as shown below:

const characters =
  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
const length = 9;
let randomStr = "";

for (let i = 0; i < length; i++) {}

In each iteration, you need to generate a random number between 0 and characters.length - 1. You will use this number to pick a character from the characters variable that you will add to the randomStr variable.

The code inside the for loop will be as follows:

const characters =
  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
const length = 9;
let randomStr = "";

for (let i = 0; i < length; i++) {
  const randomNum = Math.floor(Math.random() * characters.length);
  randomStr += characters[randomNum];
}

console.log(randomStr); // will be different with each execution

And that’s how you generate an alphanumeric random string using JavaScript. You can change the length variable value to change how many characters you have in the random string.

JavaScript random letter-only string

To generate a letter-only string, you can use the same method as generating a random alphanumeric string above. You just need to remove the numbers 0 to 9 from the characters variable:

const characters = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
const length = 9;
let randomStr = "";

for (let i = 0; i < length; i++) {
  const randomNum = Math.floor(Math.random() * characters.length);
  randomStr += characters[randomNum];
}

console.log(randomStr); // will be different with each execution

And that’s how you can generate a random letter-only string 😉

Original article source at: https://sebhastian.com/

#javascript #string #random 

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How to Code A Random String Generator Program using JavaScript
Chloe  Butler

Chloe Butler

1667425440

Pdf2gerb: Perl Script Converts PDF Files to Gerber format

pdf2gerb

Perl script converts PDF files to Gerber format

Pdf2Gerb generates Gerber 274X photoplotting and Excellon drill files from PDFs of a PCB. Up to three PDFs are used: the top copper layer, the bottom copper layer (for 2-sided PCBs), and an optional silk screen layer. The PDFs can be created directly from any PDF drawing software, or a PDF print driver can be used to capture the Print output if the drawing software does not directly support output to PDF.

The general workflow is as follows:

  1. Design the PCB using your favorite CAD or drawing software.
  2. Print the top and bottom copper and top silk screen layers to a PDF file.
  3. Run Pdf2Gerb on the PDFs to create Gerber and Excellon files.
  4. Use a Gerber viewer to double-check the output against the original PCB design.
  5. Make adjustments as needed.
  6. Submit the files to a PCB manufacturer.

Please note that Pdf2Gerb does NOT perform DRC (Design Rule Checks), as these will vary according to individual PCB manufacturer conventions and capabilities. Also note that Pdf2Gerb is not perfect, so the output files must always be checked before submitting them. As of version 1.6, Pdf2Gerb supports most PCB elements, such as round and square pads, round holes, traces, SMD pads, ground planes, no-fill areas, and panelization. However, because it interprets the graphical output of a Print function, there are limitations in what it can recognize (or there may be bugs).

See docs/Pdf2Gerb.pdf for install/setup, config, usage, and other info.


pdf2gerb_cfg.pm

#Pdf2Gerb config settings:
#Put this file in same folder/directory as pdf2gerb.pl itself (global settings),
#or copy to another folder/directory with PDFs if you want PCB-specific settings.
#There is only one user of this file, so we don't need a custom package or namespace.
#NOTE: all constants defined in here will be added to main namespace.
#package pdf2gerb_cfg;

use strict; #trap undef vars (easier debug)
use warnings; #other useful info (easier debug)


##############################################################################################
#configurable settings:
#change values here instead of in main pfg2gerb.pl file

use constant WANT_COLORS => ($^O !~ m/Win/); #ANSI colors no worky on Windows? this must be set < first DebugPrint() call

#just a little warning; set realistic expectations:
#DebugPrint("${\(CYAN)}Pdf2Gerb.pl ${\(VERSION)}, $^O O/S\n${\(YELLOW)}${\(BOLD)}${\(ITALIC)}This is EXPERIMENTAL software.  \nGerber files MAY CONTAIN ERRORS.  Please CHECK them before fabrication!${\(RESET)}", 0); #if WANT_DEBUG

use constant METRIC => FALSE; #set to TRUE for metric units (only affect final numbers in output files, not internal arithmetic)
use constant APERTURE_LIMIT => 0; #34; #max #apertures to use; generate warnings if too many apertures are used (0 to not check)
use constant DRILL_FMT => '2.4'; #'2.3'; #'2.4' is the default for PCB fab; change to '2.3' for CNC

use constant WANT_DEBUG => 0; #10; #level of debug wanted; higher == more, lower == less, 0 == none
use constant GERBER_DEBUG => 0; #level of debug to include in Gerber file; DON'T USE FOR FABRICATION
use constant WANT_STREAMS => FALSE; #TRUE; #save decompressed streams to files (for debug)
use constant WANT_ALLINPUT => FALSE; #TRUE; #save entire input stream (for debug ONLY)

#DebugPrint(sprintf("${\(CYAN)}DEBUG: stdout %d, gerber %d, want streams? %d, all input? %d, O/S: $^O, Perl: $]${\(RESET)}\n", WANT_DEBUG, GERBER_DEBUG, WANT_STREAMS, WANT_ALLINPUT), 1);
#DebugPrint(sprintf("max int = %d, min int = %d\n", MAXINT, MININT), 1); 

#define standard trace and pad sizes to reduce scaling or PDF rendering errors:
#This avoids weird aperture settings and replaces them with more standardized values.
#(I'm not sure how photoplotters handle strange sizes).
#Fewer choices here gives more accurate mapping in the final Gerber files.
#units are in inches
use constant TOOL_SIZES => #add more as desired
(
#round or square pads (> 0) and drills (< 0):
    .010, -.001,  #tiny pads for SMD; dummy drill size (too small for practical use, but needed so StandardTool will use this entry)
    .031, -.014,  #used for vias
    .041, -.020,  #smallest non-filled plated hole
    .051, -.025,
    .056, -.029,  #useful for IC pins
    .070, -.033,
    .075, -.040,  #heavier leads
#    .090, -.043,  #NOTE: 600 dpi is not high enough resolution to reliably distinguish between .043" and .046", so choose 1 of the 2 here
    .100, -.046,
    .115, -.052,
    .130, -.061,
    .140, -.067,
    .150, -.079,
    .175, -.088,
    .190, -.093,
    .200, -.100,
    .220, -.110,
    .160, -.125,  #useful for mounting holes
#some additional pad sizes without holes (repeat a previous hole size if you just want the pad size):
    .090, -.040,  #want a .090 pad option, but use dummy hole size
    .065, -.040, #.065 x .065 rect pad
    .035, -.040, #.035 x .065 rect pad
#traces:
    .001,  #too thin for real traces; use only for board outlines
    .006,  #minimum real trace width; mainly used for text
    .008,  #mainly used for mid-sized text, not traces
    .010,  #minimum recommended trace width for low-current signals
    .012,
    .015,  #moderate low-voltage current
    .020,  #heavier trace for power, ground (even if a lighter one is adequate)
    .025,
    .030,  #heavy-current traces; be careful with these ones!
    .040,
    .050,
    .060,
    .080,
    .100,
    .120,
);
#Areas larger than the values below will be filled with parallel lines:
#This cuts down on the number of aperture sizes used.
#Set to 0 to always use an aperture or drill, regardless of size.
use constant { MAX_APERTURE => max((TOOL_SIZES)) + .004, MAX_DRILL => -min((TOOL_SIZES)) + .004 }; #max aperture and drill sizes (plus a little tolerance)
#DebugPrint(sprintf("using %d standard tool sizes: %s, max aper %.3f, max drill %.3f\n", scalar((TOOL_SIZES)), join(", ", (TOOL_SIZES)), MAX_APERTURE, MAX_DRILL), 1);

#NOTE: Compare the PDF to the original CAD file to check the accuracy of the PDF rendering and parsing!
#for example, the CAD software I used generated the following circles for holes:
#CAD hole size:   parsed PDF diameter:      error:
#  .014                .016                +.002
#  .020                .02267              +.00267
#  .025                .026                +.001
#  .029                .03167              +.00267
#  .033                .036                +.003
#  .040                .04267              +.00267
#This was usually ~ .002" - .003" too big compared to the hole as displayed in the CAD software.
#To compensate for PDF rendering errors (either during CAD Print function or PDF parsing logic), adjust the values below as needed.
#units are pixels; for example, a value of 2.4 at 600 dpi = .0004 inch, 2 at 600 dpi = .0033"
use constant
{
    HOLE_ADJUST => -0.004 * 600, #-2.6, #holes seemed to be slightly oversized (by .002" - .004"), so shrink them a little
    RNDPAD_ADJUST => -0.003 * 600, #-2, #-2.4, #round pads seemed to be slightly oversized, so shrink them a little
    SQRPAD_ADJUST => +0.001 * 600, #+.5, #square pads are sometimes too small by .00067, so bump them up a little
    RECTPAD_ADJUST => 0, #(pixels) rectangular pads seem to be okay? (not tested much)
    TRACE_ADJUST => 0, #(pixels) traces seemed to be okay?
    REDUCE_TOLERANCE => .001, #(inches) allow this much variation when reducing circles and rects
};

#Also, my CAD's Print function or the PDF print driver I used was a little off for circles, so define some additional adjustment values here:
#Values are added to X/Y coordinates; units are pixels; for example, a value of 1 at 600 dpi would be ~= .002 inch
use constant
{
    CIRCLE_ADJUST_MINX => 0,
    CIRCLE_ADJUST_MINY => -0.001 * 600, #-1, #circles were a little too high, so nudge them a little lower
    CIRCLE_ADJUST_MAXX => +0.001 * 600, #+1, #circles were a little too far to the left, so nudge them a little to the right
    CIRCLE_ADJUST_MAXY => 0,
    SUBST_CIRCLE_CLIPRECT => FALSE, #generate circle and substitute for clip rects (to compensate for the way some CAD software draws circles)
    WANT_CLIPRECT => TRUE, #FALSE, #AI doesn't need clip rect at all? should be on normally?
    RECT_COMPLETION => FALSE, #TRUE, #fill in 4th side of rect when 3 sides found
};

#allow .012 clearance around pads for solder mask:
#This value effectively adjusts pad sizes in the TOOL_SIZES list above (only for solder mask layers).
use constant SOLDER_MARGIN => +.012; #units are inches

#line join/cap styles:
use constant
{
    CAP_NONE => 0, #butt (none); line is exact length
    CAP_ROUND => 1, #round cap/join; line overhangs by a semi-circle at either end
    CAP_SQUARE => 2, #square cap/join; line overhangs by a half square on either end
    CAP_OVERRIDE => FALSE, #cap style overrides drawing logic
};
    
#number of elements in each shape type:
use constant
{
    RECT_SHAPELEN => 6, #x0, y0, x1, y1, count, "rect" (start, end corners)
    LINE_SHAPELEN => 6, #x0, y0, x1, y1, count, "line" (line seg)
    CURVE_SHAPELEN => 10, #xstart, ystart, x0, y0, x1, y1, xend, yend, count, "curve" (bezier 2 points)
    CIRCLE_SHAPELEN => 5, #x, y, 5, count, "circle" (center + radius)
};
#const my %SHAPELEN =
#Readonly my %SHAPELEN =>
our %SHAPELEN =
(
    rect => RECT_SHAPELEN,
    line => LINE_SHAPELEN,
    curve => CURVE_SHAPELEN,
    circle => CIRCLE_SHAPELEN,
);

#panelization:
#This will repeat the entire body the number of times indicated along the X or Y axes (files grow accordingly).
#Display elements that overhang PCB boundary can be squashed or left as-is (typically text or other silk screen markings).
#Set "overhangs" TRUE to allow overhangs, FALSE to truncate them.
#xpad and ypad allow margins to be added around outer edge of panelized PCB.
use constant PANELIZE => {'x' => 1, 'y' => 1, 'xpad' => 0, 'ypad' => 0, 'overhangs' => TRUE}; #number of times to repeat in X and Y directions

# Set this to 1 if you need TurboCAD support.
#$turboCAD = FALSE; #is this still needed as an option?

#CIRCAD pad generation uses an appropriate aperture, then moves it (stroke) "a little" - we use this to find pads and distinguish them from PCB holes. 
use constant PAD_STROKE => 0.3; #0.0005 * 600; #units are pixels
#convert very short traces to pads or holes:
use constant TRACE_MINLEN => .001; #units are inches
#use constant ALWAYS_XY => TRUE; #FALSE; #force XY even if X or Y doesn't change; NOTE: needs to be TRUE for all pads to show in FlatCAM and ViewPlot
use constant REMOVE_POLARITY => FALSE; #TRUE; #set to remove subtractive (negative) polarity; NOTE: must be FALSE for ground planes

#PDF uses "points", each point = 1/72 inch
#combined with a PDF scale factor of .12, this gives 600 dpi resolution (1/72 * .12 = 600 dpi)
use constant INCHES_PER_POINT => 1/72; #0.0138888889; #multiply point-size by this to get inches

# The precision used when computing a bezier curve. Higher numbers are more precise but slower (and generate larger files).
#$bezierPrecision = 100;
use constant BEZIER_PRECISION => 36; #100; #use const; reduced for faster rendering (mainly used for silk screen and thermal pads)

# Ground planes and silk screen or larger copper rectangles or circles are filled line-by-line using this resolution.
use constant FILL_WIDTH => .01; #fill at most 0.01 inch at a time

# The max number of characters to read into memory
use constant MAX_BYTES => 10 * M; #bumped up to 10 MB, use const

use constant DUP_DRILL1 => TRUE; #FALSE; #kludge: ViewPlot doesn't load drill files that are too small so duplicate first tool

my $runtime = time(); #Time::HiRes::gettimeofday(); #measure my execution time

print STDERR "Loaded config settings from '${\(__FILE__)}'.\n";
1; #last value must be truthful to indicate successful load


#############################################################################################
#junk/experiment:

#use Package::Constants;
#use Exporter qw(import); #https://perldoc.perl.org/Exporter.html

#my $caller = "pdf2gerb::";

#sub cfg
#{
#    my $proto = shift;
#    my $class = ref($proto) || $proto;
#    my $settings =
#    {
#        $WANT_DEBUG => 990, #10; #level of debug wanted; higher == more, lower == less, 0 == none
#    };
#    bless($settings, $class);
#    return $settings;
#}

#use constant HELLO => "hi there2"; #"main::HELLO" => "hi there";
#use constant GOODBYE => 14; #"main::GOODBYE" => 12;

#print STDERR "read cfg file\n";

#our @EXPORT_OK = Package::Constants->list(__PACKAGE__); #https://www.perlmonks.org/?node_id=1072691; NOTE: "_OK" skips short/common names

#print STDERR scalar(@EXPORT_OK) . " consts exported:\n";
#foreach(@EXPORT_OK) { print STDERR "$_\n"; }
#my $val = main::thing("xyz");
#print STDERR "caller gave me $val\n";
#foreach my $arg (@ARGV) { print STDERR "arg $arg\n"; }

Download Details:

Author: swannman
Source Code: https://github.com/swannman/pdf2gerb

License: GPL-3.0 license

#perl 

anita maity

anita maity

1619614811

Random Password Generator Using JavaScript, HTML & CSS

Random Password Generator is a program that automatically generates a password randomly. Those generated passwords are mix with numbers, alphabets, symbols, and punctuations. This type of program helps the user to create a strong password.

Step By Step Tutorial :https://cutt.ly/ZbiDeyL

#password generator #random password generator #python password generator #random password generator javascript #html #javascript

Gordon  Taylor

Gordon Taylor

1669470540

How to Code A Random String Generator Program using JavaScript

Code recipe: JavaScript random string generator

There are several ways to generate a random string with JavaScript, depending on the requirements you need to meet.

You can generate both random alphanumeric string, which is a combination of letter and numbers, and you can also generate a letter-only string. This tutorial will help you to learn both.

JavaScript random alphanumeric string

You can generate a random alphanumeric string with JavaScript by first creating a variable that contains all the characters you want to include in the random string.

For example, the following characters variable contains the numbers 0 to 9 and letters A to Z both in upper and lower cases:

const characters =
  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";

Once you settled on the characters you want to include in your random string, you need to determine the length of the random string. For this tutorial, let’s generate a random string with 9 characters :

const characters =
  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
const length = 9;

Now you need to create another variable that contains the random string. Just initialize the variable with an empty string like this:

const characters =
  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
const length = 9;
let randomStr = "";

It’s time to generate the random string. Write a for loop that will iterate as long as the value of length variable as shown below:

const characters =
  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
const length = 9;
let randomStr = "";

for (let i = 0; i < length; i++) {}

In each iteration, you need to generate a random number between 0 and characters.length - 1. You will use this number to pick a character from the characters variable that you will add to the randomStr variable.

The code inside the for loop will be as follows:

const characters =
  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
const length = 9;
let randomStr = "";

for (let i = 0; i < length; i++) {
  const randomNum = Math.floor(Math.random() * characters.length);
  randomStr += characters[randomNum];
}

console.log(randomStr); // will be different with each execution

And that’s how you generate an alphanumeric random string using JavaScript. You can change the length variable value to change how many characters you have in the random string.

JavaScript random letter-only string

To generate a letter-only string, you can use the same method as generating a random alphanumeric string above. You just need to remove the numbers 0 to 9 from the characters variable:

const characters = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
const length = 9;
let randomStr = "";

for (let i = 0; i < length; i++) {
  const randomNum = Math.floor(Math.random() * characters.length);
  randomStr += characters[randomNum];
}

console.log(randomStr); // will be different with each execution

And that’s how you can generate a random letter-only string 😉

Original article source at: https://sebhastian.com/

#javascript #string #random 

Wilford  Pagac

Wilford Pagac

1602673200

Understanding JavaScript Generators And Basic Use-Cases

In one of my many deep-dives about JavaScript, I came across generators. They looked interesting.

Then, I looked for some use-cases for generators. And looked. And looked.

Eventually, I found a simple generator throttle example. After all this research, I resolved to see how I could use them. Since I was working on an Asynchronous JavaScript talk (JavaScript Enjoys Your Tears), I wrote a state machine to facilitate positioning within the slide deck and managing font size on the presentation side.

What I found is documented here …

Generators are functions which can be exited and later re-entered. Their context (variable bindings) will be saved across re-entrances. - MDN.

The ability of functions to be paused and then resumed again. A generator returns an iterator. On creation, the code inside the generator is not executed.

  • Solves “reasoning about” issues.
  • Allows for non-“run-to-completion” behavior. Localized blocking only.
  • Syntactic form of a state machine.
  • Cooperative concurrency versus preemptive concurrency.

Advantages of Generators

Lazy Evaluation

This is an evaluation model which delays the evaluation of an expression until its value is needed. That is, if the value is not needed, it will not exist. It is calculated on demand.

Memory Efficient

A direct consequence of Lazy Evaluation is that generators are memory efficient. The only values generated are those that are needed. With normal functions, all the values must be pre-generated and kept around in case they need to be used later. However, with generators, computation is deferred.

Use-Cases

Here are some Generator use-cases …

Infinitely Repeating Array

This is the article (by Shawn Reisner) that got me interested in this topic in the first place.

#javascript #web-development #generator #use-cases #coding #productivity #es6 #code-quality

Lowa Alice

Lowa Alice

1624399200

JavaScript Strings Tutorial

JavaScript Strings

📺 The video in this post was made by Programming with Mosh
The origin of the article: https://www.youtube.com/watch?v=09BwruU4kiY&list=PLTjRvDozrdlxEIuOBZkMAK5uiqp8rHUax&index=6
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#javascript #strings #javascript strings #javascript strings tutorial