I would like transform string with uppercase to string with underscore like:
- "blablaBlabla" to "blabla_blabla"
- "firstName" to "first_name"
And conversely:
- "blabla_blabla" to "blablaBlabla"
- "first_Name" to "firstName"
I use Typescript, but I think for that, there is no difference with the Javascript.
Thank's in advance.
Jérémy.
You could get all the upper case letters with [AZ]
and replace
the match with _ + m.toLowerCase()
To change it the other way, match all _([az])
to get the alphabet to a capturing group. And then use toUpperCase
on the capture
function trasnform1(str) { return str.replace(/[AZ]/g, (m) => '_' + m.toLowerCase()) } function trasnform2(str) { return str.replace(/_([az])/g, (m, p1) => p1.toUpperCase()) } console.log(trasnform1("blablaBlabla")) console.log(trasnform1("firstName")) console.log(trasnform2("blabla_blabla")) console.log(trasnform2("first_name"))
let word = "firstName"; let output = ""; // for conversion for (let i = 0; i < word.length; i++) { if (word[i] === word[i].toUpperCase()) { output += "_" + word[i].toLowerCase(); } else { output += word[i]; } } console.log(output); let source = output; output = ""; //for reversion for (let i = 0; i < source.length; i++) { if (source[i] === "_") { i++; output += source[i].toUpperCase(); } else { output += source[i]; } } console.log(output);
// Camel to snake and snake to camel case
function changeCasing(input) {
if (!input) {
return '';
}
if (input.indexOf('_') > -1) {
const regex = new RegExp('_.', 'gm');
return input.replace(regex, (match) => {
const char = match.replace("_", "");
return char.toUpperCase();
});
} else {
const regex = new RegExp('[A-Z]', 'gm');
return input.replace(regex, (match) => {
return `_${match.toLowerCase()}`;
});
}
}
This is example written in TypeScript. It's more readable using method chaining.
export const snake2Camel = (snake: string): string => {
return snake.split('').reduce((prev: string, cur: string) => {
if (prev.includes("_")) {
prev = prev.substring(0, prev.length - 1);
cur = cur.toUpperCase();
}
return prev + cur;
}, "");
};
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