how to use the cond function from the lodash library in typescript

The cond function in the Lodash library allows us to create a conditional function based on an array of [predicate, transformer] pairs. Here's how you can use it in Typescript:

First, make sure you have installed the lodash library:

npm install lodash
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Then, import the cond function from the library:

index.ts
import cond from 'lodash/cond';
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Next, define the array of [predicate, transformer] pairs. The predicate function will take one argument and return a boolean value, and the transformer function will take the same argument and return the result:

index.ts
const conditions = [
  [ (val: number) => val < 0, (val: number) => `${val} is a negative number` ],
  [ (val: number) => val > 10, (val: number) => `${val} is greater than 10` ],
  [ (val: number) => val === 0, (val: number) => `${val} is zero` ],
  [ () => true, (val: any) => `I don't know what to do with ${val}` ],
];
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In this example, we have four conditions:

• If the value is less than zero, return a string indicating that it's a negative number
• If the value is greater than ten, return a string indicating that it's greater than 10
• If the value is zero, return a string indicating that it's zero
• If none of the above conditions match, return a generic message

Finally, pass the array of conditions to the cond function to create the conditional function:

index.ts
const transformer = cond(conditions);
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Now you can use the transformer function to transform any value based on the conditions you specified:

index.ts
console.log(transformer(-5)); // "-5 is a negative number"
console.log(transformer(15)); // "15 is greater than 10"
console.log(transformer(0)); // "0 is zero"
console.log(transformer('foo')); // "I don't know what to do with foo"
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