Why when i call a function with returning value, my onclick event doesn't work?

Question

I minified my work in this simple code that represent my problem:

runSomething();

function runSomething(){

    function getRandom(){
        var random = Math.floor((Math.random())*10);
        return random;
    };        

    document.onclick = getRandom();
};

There is a external function ( runSomething() ) that contains the next:

• A function called getRandom that returns a number between 0 - 9 (that i'm using to a select a random item of a array)
• And a the document.onclick = getRandom(); that what is supposed to do, is RUN getRandom(); each time i click any place of the document, to get another new value

But what happens? the document.onclick = getRandom(); just run once (when the document is being loaded) but nothing happens when a click the document

And getRandom() must not be fired when the document is being loaded, because that function is fired in other part of the script, and thats mean that i will get 2 differents new values (remember that getRandom() return different numbers each time that is fired)

What i'm doing wrong?

PS I still a rookie in JS

PPS Sorry for my english

Answer 1

Remove the ()

document.onclick = getRandom;

The () will invoke the function immediately on load, you have to pass the function along.

Answer 2

分配onClick时，需要分配函数而不是执行它并分配返回值（这是你的()所做的）：

document.onclick = getRandom;