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I got this warning from variable cipher when I was trying to change a string character at specified index.
const emojis: string[] = [/* values */];
function revealOriginEmojis(cipher: string): string {
for(let i = 0; i < cipher.length; i++){
let index: number = emojis.indexOf(cipher[i]);
cipher[i] = emojis[index];
}
return cipher;
}
So, should I create a new string variable or any better solutions? Thank you so much
613
The idea of the index signatures is to type objects of unknown structure when you only know the key and value types. An index signature fits the case of the salary parameter: the function should accept salary objects of different structures — only that values to be numbers.
The error "Property is incompatible with index signature" occurs when a property is not compatible with the specified type of the index signature. To solve the error, change the type of the property or use a union to update the type in the index signature.
The indexing type is itself a type, so we can use unions, keyof , or other types entirely: type I1 = Person ["age" | "name"]; type I1 = string | number. type I2 = Person [keyof Person ]; type I2 = string | number | boolean.
The "Type 'string' is not assignable to type" TypeScript error occurs when we try to assign a value of type string to something that expects a different type, e.g. a more specific string literal type or an enum. To solve the error use a const or a type assertion. Here is the first example of how the error occurs.
As soon as you have a string index signature, all explicit members must also conform to that index signature. Property 'fooMethod' of type ' (fooParam: string): void' is not assignable to string index type 'string'
Also, we can designate index signatures as readonly so that they can be written to when the object with a type with indexable types is initialized but not after.
An index signature parameter type must be 'string', 'number', 'symbol', or a template literal type. An index signature parameter type must be 'string', 'number', 'symbol', or a template literal type. 3. Index signature caveats The index signatures in TypeScript have a few caveats you should be aware of.
If we have both number and string index signatures, then the string indexable signature must have the return type that’s the super-type of the one with the number index signature so that we get consistent types for objects when we access properties. Touched very intresting points, thanks!
A string is a primitive value, it's immutable.
you can convert it into array of chars, edit some elements of the array and convert back the array into string.
const cipherChars = [...cipher]; // convert into array
cipherChars[2] = 'X'; // alter array
cipher = cipherChars.join(''); // convert back into string
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