我已经在JavaScript中创建了以下功能,该功能可以正常工作:
<script>
function add(a, b, c) {
document.write('A: ' + a + '<br>');
document.write('B: ' + b + '<br>');
document.write('C: ' + c + '<br>');
}
add(10, 20);
</script>
A: 10
B: 20
C: undefined
但是,JavaScript中的以下功能未按预期方式工作,因此未显示undefined
值
<script>
function addArray(a = [101]) {
document.write('A: ' + a[0] + '<br>');
document.write('B: ' + a + '<br>');
document.write('C: ' + c + '<br>');
}
addArray([110]);
</script>
A: 110
B: 110
根据我的理解,输出应如下:
A: 110
B: 110
C: undefined
而且,在以上示例中,a[0]
和a
之间有什么区别?
The difference between a[0] and a is that a[0] is displaying the first index value of an
array and a is displaying all the values of the array.
Imagine A=[100,200]
document.write('A: ' + a[0] + '<br>');
Would write 100
document.write('A: ' + a + '<br>');
Would write 100,200
从未声明c
function addArray(a=[101],c) {
document.write('A: ' + a[0] + '<br>');
document.write('B: ' + a + '<br>');
document.write('C: ' + c + '<br>');
}
addArray([110,120]);