CODEWITHSUNDEEP
javascripttimercounter
shmink
shmink

Reputation: 301

Get a new value every n seconds

I have a web page where I display a quote. I pick one of the quotes at random. At the moment it does this every time the web page is loaded, I would now prefer that it picks one every 5 seconds. I'm a beginner and not sure how best to implement this nor the appropriate function. setInterval?, setTimeout?, delay?, wait?

var quotes = JSON.parse('{\
    "0": "Don\'t worry about what anybody else is going to do. The best way to predict the future is to invent it. -- Alan Kay", \
    "1": "Keep away from people who try to belittle your ambitions. Small people always do that, but the really great make you feel that you, too, can become great. -- Mark Twain", \
    "2": "No problem should ever have to be solved twice. -- Eric S. Raymond, How to become a hacker", \
    "3": "Attitude is no substitute for competence. -- Eric S. Raymond, How to become a hacker", \
    "4": "It is said that the real winner is the one who lives in today but able to see tomorrow. -- Juan Meng", \
    "5": "Fools ignore complexity. Pragmatists suffer it. Some can avoid it. Geniuses remove it. -- Alan J.Perlis(Epigrams in programming)", \
    "6": "A year spent in artificial intelligence is enough to make one believe in God. -- Alan J.Perlis(Epigrams in programming)" \
}');

function getRandomArbitrary(min, max) {
    return Math.random() * (max - min) + min;
}
var num = Math.floor(getRandomArbitrary(0, Object.keys(quotes).length));

document.getElementById('quote').innerHTML = quotes[num];

As mentioned I would now like the value in ID 'quote' to be updated every 5 seconds. So I would assume that means updating the num var?

Upvotes: 0

Views: 186

Answers (3)

etarhan
etarhan

Reputation: 4176

You can indeed use setInterval to accomplish this. Try adding a setInterval like so:

var quotes = JSON.parse(
      '{\
      "0": "Don\'t worry about what anybody else is going to do. The best way to predict the future is to invent it. -- Alan Kay", \
      "1": "Keep away from people who try to belittle your ambitions. Small people always do that, but the really great make you feel that you, too, can become great. -- Mark Twain", \
      "2": "No problem should ever have to be solved twice. -- Eric S. Raymond, How to become a hacker", \
      "3": "Attitude is no substitute for competence. -- Eric S. Raymond, How to become a hacker", \
      "4": "It is said that the real winner is the one who lives in today but able to see tomorrow. -- Juan Meng", \
      "5": "Fools ignore complexity. Pragmatists suffer it. Some can avoid it. Geniuses remove it. -- Alan J.Perlis(Epigrams in programming)", \
      "6": "A year spent in artificial intelligence is enough to make one believe in God. -- Alan J.Perlis(Epigrams in programming)" \
    }'
    );
    
    function getRandomArbitrary(min, max) {
      return Math.random() * (max - min) + min;
    }
    
    function updateQuote() {
      var num = Math.floor(getRandomArbitrary(0, Object.keys(quotes).length));
      document.getElementById("quote").innerHTML = quotes[num];
    }
    
    updateQuote();
    setInterval(updateQuote, 5000);
<h3 id="quote"></h3>

The second parameter of setInterval accepts number of milliseconds, so in your case this is 5000. Read more here

Upvotes: 1

brk
brk

Reputation: 50291

You can use setInterval which repeatedly calls a function or executes a code snippet, with a fixed time delay & inside the callback function get a new num every time.

var quotes = JSON.parse('{\
    "0": "Don\'t worry about what anybody else is going to do. The best way to predict the future is to invent it. -- Alan Kay", \
    "1": "Keep away from people who try to belittle your ambitions. Small people always do that, but the really great make you feel that you, too, can become great. -- Mark Twain", \
    "2": "No problem should ever have to be solved twice. -- Eric S. Raymond, How to become a hacker", \
    "3": "Attitude is no substitute for competence. -- Eric S. Raymond, How to become a hacker", \
    "4": "It is said that the real winner is the one who lives in today but able to see tomorrow. -- Juan Meng", \
    "5": "Fools ignore complexity. Pragmatists suffer it. Some can avoid it. Geniuses remove it. -- Alan J.Perlis(Epigrams in programming)", \
    "6": "A year spent in artificial intelligence is enough to make one believe in God. -- Alan J.Perlis(Epigrams in programming)" \
}');

function getRandomArbitrary(min, max) {
  return Math.random() * (max - min) + min;
}
// you need this value only once so no need to get it at every interval
let maxVal =Object.keys(quotes).length);
setInterval(() => {
  var num = Math.floor(getRandomArbitrary(0,maxVal);
  document.getElementById('quote').innerHTML = quotes[num];
}, 5000)
<div id='quote'></div>

Upvotes: 0

Hari Prathap
Hari Prathap

Reputation: 102

@shmink, It is good that you have come up with code to populate a div, I have added a snippet to call that in setInterval which updates every 5s. Make sure you call clearInterval to stop the setInterval once you move away(Move to some other page, close).

var quotes = JSON.parse('{\
    "0": "Don\'t worry about what anybody else is going to do. The best way to predict the future is to invent it. -- Alan Kay", \
    "1": "Keep away from people who try to belittle your ambitions. Small people always do that, but the really great make you feel that you, too, can become great. -- Mark Twain", \
    "2": "No problem should ever have to be solved twice. -- Eric S. Raymond, How to become a hacker", \
    "3": "Attitude is no substitute for competence. -- Eric S. Raymond, How to become a hacker", \
    "4": "It is said that the real winner is the one who lives in today but able to see tomorrow. -- Juan Meng", \
    "5": "Fools ignore complexity. Pragmatists suffer it. Some can avoid it. Geniuses remove it. -- Alan J.Perlis(Epigrams in programming)", \
    "6": "A year spent in artificial intelligence is enough to make one believe in God. -- Alan J.Perlis(Epigrams in programming)" \
}');

function updateUI() {
var num = Math.floor(getRandomArbitrary(0, Object.keys(quotes).length));

document.getElementById('quote').innerHTML = quotes[num];
}

function getRandomArbitrary(min, max) {
    return Math.random() * (max - min) + min;
}

var interval = setInterval(updateUI, 5000);

//cleanup
//clearInterval(interval);
<div id="quote"></div>

Upvotes: 0

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