Javascript: call vs bind vs apply

  March 20, 2023 Raaz   , , ,   No comments   Edit

 Hello Everyone, 

I came across a snippet where code have .call() method.

Thought its been a while since I went through their understanding, via this article I am explaining with examples what call, bind and apply does in javascript.

Please read comments for understanding.

Hope it helps.

var obj = {
name: "Raja",
sayHello: function(args) {
console.log(`Hello ${this.name}, How are you doing `);
},
};

// call : Changing the context::this scope to the argument we are passing.
// normal

obj.sayHello() // Hello Raja, How are you doing ?
obj.sayHello.call({name : "Rajasekhar"}); // Hello Rajasekhar, How are you doing ?

var obj = {
name: "Raja",
sayHello: function(args) {
console.log(`Hello ${this.name}, How are you doing ? ${args}`);
},
};
// apply: same as call, we can also pass arguments as 2nd argument
obj.sayHello.apply({ name: "Rajasekhar" }, ["Testing"]); // Hello Rajasekhar, How are you doing ? Testing


// bind: Change function definition to a different context
// you can change the definition once

var obj = {
name: "Raja",
sayHello: function(args) {
console.log(`Hello ${this.name}, How are you doing ? ${args}`);
},
};

var contxt = {"name" : "ApplyContext:)"};
var newHello = obj.sayHello.bind(contxt);
newHello("Good Day!!!"); // Hello ApplyContext:), How are you doing ? Good Day!!!

GoLang: Quick gist on Difference between Marshal, Unmarshal, Encoder and Decoder

  March 08, 2023 Raaz   , , , , ,   No comments   Edit
Summary: Marshal, Unmarshal and Encode, Decode

Summary: Marshal, Unmarshal and Encode, Decode

  • Marshal: Convert struct/map interface data into JSON.
  • Unmarshal: Convert JSON data into struct/map

If reading from a file involved, then you read it in []byte format. To read from a file

  • using os.Open open the file.

  • then read all the data using io.ReadAll method.

  • Encoder and Decoder kind of do reading/writing internally. More like a simplified version of Marshal and Unmarshal.

  • Encoder converts the struct/map into JSON and automatically writes into io.Writer

  • Decoder reads from io.Writer and convert the JSON data into struct/map interface.

If there is a byte slice to work with, use Marshal and Unmarshal. If there is an io.Writer or an io.Reader, use Encode and Decode.

Ref: https://blog.devgenius.io/to-unmarshal-or-to-decode-json-processing-in-go-explained-e92fab5b648f

GoLang: How to render a web template using Gin framework and render data from map ?

  March 07, 2023 Raaz   , , , , ,   No comments   Edit

 I have struggled lot of time, to break this into working modal. So below code, is working example where you can have your data in a slice of URLs and render that data using Go Templates. 

I am giving a skeleton HTML template, not adding any thing extra. 

I believe the code itself is self explanatory, if any questions, please dont hesitate to ask.


main.go

package main

import (
"log"
"net/http"

"github.com/gin-gonic/gin"
)

type URL struct {
Name string
Url string
}

var URLs = []URL{
{Name: "google", Url: "google.com"},
{Name: "yahoo", Url: "yahoo.com"},
{Name: "gmail", Url: "gmail.com"},
}

func main() {

router := gin.Default()
router.LoadHTMLGlob("templates/*")
router.GET("/", bookmarks)
router.GET("/hello", func(c *gin.Context) {
c.HTML(http.StatusOK, "index.tmpl", gin.H{
"title": "Main website",
"Items": URLs,
})
})

log.Fatal(router.Run(":8000"))
}

func bookmarks(c *gin.Context) {
c.HTML(http.StatusOK, "index.tmpl", gin.H{
"title": "Bookmarks",
"URLs": URLs,
})
}

Go Templates will be stored inside templates directory, so create a templates directory where you have your main.go file and have that file as below 

index.tmpl


<html>
<h1>
{{ .title }}
</h1>
<body>
{{ range .URLs}}
{{.Name}}
{{.Url}}
{{end}}
</body>
</html>

Hope it helps.

Thank you.
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