为什么我不能在HTML中使用被称为'evaluate'的JS函数？

Question

I'm kind of curious why this doesn't work

JavaScript:

function evaluate(){
    console.log(42);
}

HTML:

<a onclick="evaluate()">Click Me!</a>

Is evaluate a reserved keyword somewhere on the html side?

Answer 1

"evaluate" is not a reserved keyword, but when it's used in inline event handler, it happens to collide with document's evaluate function( document object is within handler's scope chain before the window object). If you don't want to change your function name, just add window context before it, ie

<a onclick="window.evaluate()">Click Me!</a>

Answer 2

document.evaluate需要解析个XML，看到在MDN参考这里 。

Answer 3

Evaluate is not a reserved word in JavaScript, document.evaluate is used to evaluate XPath expressions.

You could still name your function evaluate if you used a less obtrusive method of attaching your event handler:

var evaluate = function (){
    console.log(42);
}

document.addEventListener('click', evaluate, false);

Example