How to use signature-pad v4.0 in IE 11? [duplicate]
IE 11 does not support the class keyword and language features, according to the compatibility table.
You can force the Typescript compiler to output code that will be compatible with an older version of JavaScript using the --target option or equivalent in your build. Otherwise, you'll need to run the TS output through another transpiler (such as Babel) to produce ES5 that will run under IE.
Your compiler still seems to be compiling to es6 code which IE11 does not support
Try changing your compiler options to compile down to es5.