Typescript - correct way to set a string based on string comparison

Question

I want to check if a string is equal to another string and set a new string based on this condition.

 private myFunction( myString: string ) {

    if (myString != "someString") {
      let path:string = "/*/POST/A";
    }
    else{
      let path:string = "/*/POST/note/B";

    }
   (do something with path here)

Not sure the above is correct actually finding it pretty hard to find a decent example of this and completely new to typescript/ javascript.

let path = "/*/POST/note/B"; if (myString != "someString") { path = "/*/POST/A"; }? — Heretic Monkey
– Heretic Monkey, Commented Aug 14, 2020 at 14:32
You have to define your let variable before any condition if u want to do something with your path — Maciej Król
– Maciej Król, Commented Aug 14, 2020 at 14:37

Klaycon · Accepted Answer · 2020-08-14 14:36:57Z

2

let variables are block-scoped - they only exist within the block you declare them. So declaring let path inside of the if block or the else block won't allow you to use it later outside of the if/else.

All you need to do is declare it in the scope you want to use it and assign it in the if/else.

let path: string;
if (myString != "someString") {
  path = "/*/POST/A";
} else {
  path = "/*/POST/note/B";
}
//use path here

answered Aug 14, 2020 at 14:36

Klaycon

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Comments

ray · Accepted Answer · 2020-08-14 14:35:46Z

1

Consider using a ternary expression so you’re not declaring the variable inside the conditional:

const path:string = myString === “someString” ? “option a” : “option b”

answered Aug 14, 2020 at 14:35

ray

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2 Comments

AnonymousAlias Over a year ago

I like this, so the option a is if the string is equal to someString?

ray Over a year ago

Yes. It takes this form: condition ? value if true : value if false

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