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);
}