espterm-front-end/jssrc/utils.js

/** 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();
    }
  };
}

/** Extend an objects with options */
function extend(defaults, options) {
  var target = {};

  Object.keys(defaults).forEach(function (k) {
    target[k] = defaults[k];
  });

  Object.keys(options).forEach(function (k) {
    target[k] = options[k];
  });

  return target;
}

/** Escape string for use as literal in RegExp */
function rgxe(str) {
  return str.replace(/[\-\[\]\/\{\}\(\)\*\+\?\.\\\^\$\|]/g, "\\$&");
}

/** Format number to N decimal places, output as string */
function numfmt(x, places) {
  var pow = Math.pow(10, places);
  return Math.round(x * pow) / pow;
}

/** Get millisecond timestamp */
function msNow() {
  return +(new Date);
}

/** Get ms elapsed since msNow() */
function msElapsed(start) {
  return msNow() - start;
}

/** Shim for log base 10 */
Math.log10 = Math.log10 || function (x) {
  return Math.log(x) / Math.LN10;
};

/**
 * Perform a substitution in the given string.
 *
 * Arguments - array or list of replacements.
 * Arguments numeric keys will replace {0}, {1} etc.
 * Named keys also work, ie. {foo: "bar"} -> replaces {foo} with bar.
 *
 * Braces are added to keys if missing.
 *
 * @returns {String} result
 */
String.prototype.format = function () {
  var out = this;
  var repl = arguments;

  if (arguments.length == 1 && (Array.isArray(arguments[0]) || typeof arguments[0] == 'object')) {
    repl = arguments[0];
  }

  for (var ph in repl) {
    if (repl.hasOwnProperty(ph)) {
      var ph_orig = ph;

      if (!ph.match(/^\{.*\}$/)) {
        ph = '{' + ph + '}';
      }

      // replace all occurrences
      var pattern = new RegExp(rgxe(ph), "g");
      out = out.replace(pattern, repl[ph_orig]);
    }
  }

  return out;
};

/** HTML escape */
function e(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) {
  var 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) {
  var 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);
}