问题
Having this JS code:
document.getElementById('e1').addEventListener('click', function(){alert('1');}, false);
document.getElementById('e2').addEventListener('click', function(){alert('2');}, false);
document.getElementById('e1').click();
document.getElementById('e2').click();
I'm wondering in what order will the alerts show up - will it be in the order the events were triggered by click() or could it be random?
I'm asking about documented/standardised behaviour, not about what browsers currently implement.
回答1:
The alerts will be executed in order - 1 and then 2. This is because click event is synchronous (see here) - when .click() is issued the handler will be run immediately (look at the last paragraph here). So this code:
document.getElementById('e1').addEventListener('click', function(){alert('1');}, false);
document.getElementById('e2').addEventListener('click', function(){alert('2');}, false);
document.getElementById('e1').click();
document.getElementById('e2').click();
alert('3');
will produce the same result as
alert('1');
alert('2');
alert('3');
回答2:
I will be 1 and then 2 . http://jsfiddle.net/kkYfX/
来源：https://stackoverflow.com/questions/7077179/javascript-event-handlers-execution-order