Answers for "remove part of the string to the first new line javascript"

javascript remove all newlines

// regex global match for all variants of newlines
/\r?\n|\r/g

// example
let foo = 'bar\nbar';
foo = foo.replace(/\r?\n|\r/g, " "); /* replace all newlines with a space */
console.log(foo); /* bar bar */

javascript remove final newline from string

// Remove the trailing newline(s) from a string
str.replace(/\n*$/, "");