How to customize a string by variable in Javascript?

Question

I want to print an errormessage using javascript in certain cases. The string is german and the start depends on a variable called blfType which can be "field", "line" or "block" and the string then would be "This field already has this prerequisite" if blfType is field. I tried to do that similiar as I would do it in python:

alert("Das Feld"*(blfType == 'field') + "Die Zeile"*(blfType == 'line') + "Der Block"*(blfType == 'block')+" besitzt diese Vorraussetzung bereits");

But this would just print "NaN besitzt diese Vorraussetzung bereits". Is there any other way how I can do this in just one line or do I have to do create another Variable that takes the start of the sentence.

In this case I would do this in python like that:

const gerblfType = "Feld" if blfType === "field" else "Zeile" if blfType === "line" else "Block"

But this is also not working. Is there a smooth way in Javascript to not do it like that:

gerblfType = "Feld";
if(blfType == "line") gerblfType = "Zeile";
if(blfType == "block") gerblfType = "Block";

I think you have to do it like you just suggested, Javascript is just lame — user12146871
– user12146871, Commented Jul 30, 2021 at 17:22
const foo = { line: "Zeile", block: "Block" }; const gerblfType = foo[gerblfType] || "Feld"; — epascarello
– epascarello, Commented Jul 30, 2021 at 17:26
Also with ternary gerblfType === "line" ? "Zeile" : gerblfType === "block" ? "Block" : "Feld" — epascarello
– epascarello, Commented Jul 30, 2021 at 17:37

epascarello · Accepted Answer · 2021-07-30 18:54:25Z

1

Typical ways people would do it.

The if way

const foo = "two";

let bar = "default";
if(foo === "one") bar = "1";
else if(foo === "two") bar = "2";

console.log(bar);

With nested Ternary

const foo = "two";

const bar = foo === "one" ? "1" : foo === "two" ? "2" : "default";
console.log(bar);

With an object

const LOOK_UP = {
  one: "1",
  two: "2",
  default: "default"
};


const foo = "two";

const bar = LOOK_UP[foo] || LOOK_UP.default;
console.log(bar);

answered Jul 30, 2021 at 18:54

epascarello

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Comments

GAMELASTER · Accepted Answer · 2021-07-30 17:26:34Z

0

Use switch instead of ifs.

let gerblfType;
switch (blfType) {
  case 'line': gerblfType = 'Die Zeile'; break;
  case 'block': gerblfType = 'Der Block'; break;
  default: gerblfType = 'Das Feld'; break;
}

alert(`${gerblfType} besitzt diese Vorraussetzung bereits`);

answered Jul 30, 2021 at 17:26

GAMELASTER

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1 Comment

lxg95 Over a year ago

Yeah i know, switch case is usually better than ifs, but the goal was to keep the lines in this function as few as possible. Usually i am using switch case over if

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