Unnecessary Escapment Flagged but shouldn't be flagged

A yellow triangle warning appears in WebIDE that flags the escapement.

//unnecessaryEscapment.js
//PICO v 1x86

// A is flagged as unecessary escapment
// with a yellow triangle in the right side of WEBIDE
var A="\x31";
var B="x31";

console.log("A= ",A);
console.log("B= ",B);

The output:

>echo(0);
A=  1
B=  x31
=undefined
>