ESPTerm web interface submodule, separated to make testing and development easier
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espterm-front-end/js/utils.js

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/** Make a node */
function mk (e) {
return document.createElement(e)
}
/** Find one by query */
function qs (s) {
return document.querySelector(s)
}
/** Find all by query */
function qsa (s) {
return document.querySelectorAll(s)
}
/** Convert any to bool safely */
function bool (x) {
return (x === 1 || x === '1' || x === true || x === 'true')
}
/**
* Filter 'spacebar' and 'return' from keypress handler,
* and when they're pressed, fire the callback.
* use $(...).on('keypress', cr(handler))
*/
function cr (hdl) {
return function (e) {
if (e.which === 10 || e.which === 13 || e.which === 32) {
hdl()
}
}
}
/** HTML escape */
function esc (str) {
return $.htmlEscape(str)
}
/** Check for undefined */
function undef (x) {
return typeof x == 'undefined'
}
/** Safe json parse */
function jsp (str) {
try {
return JSON.parse(str)
} catch (e) {
console.error(e)
return null
}
}
/** Create a character from ASCII code */
function Chr (n) {
return String.fromCharCode(n)
}
/** Decode number from 2B encoding */
function parse2B (s, i = 0) {
return (s.charCodeAt(i++) - 1) + (s.charCodeAt(i) - 1) * 127
}
/** Decode number from 3B encoding */
function parse3B (s, i = 0) {
return (s.charCodeAt(i) - 1) + (s.charCodeAt(i + 1) - 1) * 127 + (s.charCodeAt(i + 2) - 1) * 127 * 127
}
/** Encode using 2B encoding, returns string. */
function encode2B (n) {
let lsb, msb
lsb = (n % 127)
n = ((n - lsb) / 127)
lsb += 1
msb = (n + 1)
return Chr(lsb) + Chr(msb)
}
/** Encode using 3B encoding, returns string. */
function encode3B (n) {
let lsb, msb, xsb
lsb = (n % 127)
n = (n - lsb) / 127
lsb += 1
msb = (n % 127)
n = (n - msb) / 127
msb += 1
xsb = (n + 1)
return Chr(lsb) + Chr(msb) + Chr(xsb)
}