Is it possible to create an array of objects that perform a function? For example, like this:
<script>
console.clear();
const acts = [
{ 'inc' : (x) => x+1 },
{ 'dec' : (x) => x-1 }
];
console.log(acts.inc(10));
console.log(acts.dec(15));
</script>
The above gives an error -- TypeError: acts.inc is not a function.
You are almost there! Create an object with "function properties" instead of an array of objects:
acts = {
'inc' : (x) => x+1,
'dec' : (x) => x-1
};
Then,
acts.inc(3)
will return:
4
In your original code, you'd have to use:
acts[0].inc(3)
because it's an array...
You can add a function to the array prototype.
Array.prototype.inc = <function>
For anyone interested, here is how I used the solution chosen along with an example output for each function created (with some options).
<!DOCTYPE html><html lang="en"><head>
<title> Array of Object Functions </title>
<meta charset="UTF-8">
<meta name="viewport" content="width-device-width,initial-scale=1.0, user-scalable=yes"/>
<!-- From: https://stackoverflow.com/questions/62824415/create-array-of-objects-with-function-actions -->
<style>
body { font-size: 1.2em; line-height: 1.6; }
</style>
</head><body>
<pre id='demo'></pre>
<script>
console.clear();
// following used only for screen display testing purposes
var former = console.log; // retain former actions of console.log
var demo=document.getElementById('demo');
console.log = function(...msg){
former(...msg); // maintains existing logging via the console. (optional)
demo.append(msg.join(' ')+'\n'); // output needs to be specified
}
// end of display testing (also shows on console.log display)
const acts = {
'inc' : (x) => x+1,
'dec' : (x) => x-1,
'mul' : (x,y) => x*y,
'div' : (x,y) => x/y, // careful with y=0 (no checks here)
'pwr' : (x,y) => x**y, // x to power of y
'deg' : (rad) => (rad * Math.PI / 360), // degrees from radians
'rad' : (deg) => (deg / Math.PI * 360), // radians from degrees
'pct' : (amt) => amt * 100, // form percentage
'bit' : (siz) => (acts.pwr(2,siz)-1).toString(2), // form bit-mask
'oct' : (dec) => dec.toString(8), // form octal
'hex' : (dec) => dec.toString(16), // form hexidecimal
'fmt' : (amt,size) => amt.toFixed(size), // number .toFixed(#) string
'cdt' : (dateInfo,locn='en-US') => dateInfo.toLocaleDateString(locn), // format US Date object
};
console.log(acts.inc(10)); // 11
console.log(acts.dec(15)); // 14
console.log(acts.mul(4,5)); // 20
console.log(acts.div(5,4)); // 1.25
console.log(acts.pwr(2,16)); // 65536
console.log(acts.deg(360)); // 3.14159...
console.log(acts.rad(Math.PI/2)); // 1.57079...
console.log(`${acts.pct(0.15)}%`); // 15%
console.log(`${acts.pct(acts.div(7,8))}%`); // 87.5%
console.log('0b'+acts.bit(8)); // 0b11111111
console.log('10.0 = 0o'+acts.oct(10),'octal'); // 0o12
console.log('0x'+acts.hex(65535)); // 0xffff
console.log(acts.fmt(Math.PI,2)); // 3.14
console.log(acts.fmt(Math.PI,4)); // 3.1416
console.log(Math.PI); // full precision PI
console.log('m/d/yyyy : ',acts.cdt(new Date())); // current date (m/d/year format) US
console.log('dd/mm/yyyy : ',acts.cdt(new Date(),'en-GB')); // date (dd/mm/year format) GB
// tests of binary range displays
console.log('\n ','----+'.repeat(6)+'--');
console.log('0b'+acts.bit(0)); // 0b0
console.log('0b'+acts.bit(0).padStart(8,'0')); // 0b00000000
console.log('0b'+acts.bit(16)); // 0b1111...1111 (length = 16 bits)
console.log('0b'+acts.bit(16).padStart(32,'0')); // 0b0111...1111
console.log('0b0'+acts.bit(31)); // 0b11111...11111 (length = 31 bits)
console.log('0b'+acts.bit(32).padStart(32,'0')); // 0b1111...1111 ( = 32 bits)
console.log('\n ','----+'.repeat(6)+'--');
console.log(`Dad's birthday: ${acts.cdt(new Date(1925,1,1))}`); // default US format
</script>
</body>
</html>
Additional comments are welcome.