对JavaScript数组splice(1,2)执行结果的疑问

Hey there! Let's clear up this confusion around splice() right away—there's a mix-up between what you expected and what the code actually does.

First, let's set the record straight: your code does NOT remove "eel" and "piranha". Let's walk through the execution step by step to see exactly what happens:

Step 1: The Initial Array #

Your starting array is:

let fish = [ "piranha", "barracuda", "koi", "eel" ];

Remember, JavaScript arrays are zero-indexed—here's how indices map to elements:

• Index 0: piranha
• Index 1: barracuda
• Index 2: koi
• Index 3: eel

Step 2: Breaking Down the splice() Call #

You’re running:

fish.splice(1, 2);

Let’s recap what each parameter does for splice():

• The first parameter (1) is the starting index where modifications begin.
• The second parameter (2) is the number of elements to remove starting from that index.

So this line tells JavaScript: "Start at index 1, and remove the next 2 elements." That means we remove:

1. Index 1: barracuda
2. Index 2: koi

Step 3: The Final Array #

After the splice() call, the fish array becomes:

["piranha", "eel"]

Why Might You Have Misinterpreted the Result? #

It’s likely you mixed up zero-indexed counting (arrays start at 0, not 1!) or maybe you inspected the array in a loop with an unexpected iteration order. Double-check how you’re viewing the final array, and make sure you’re not confusing splice() with another method like slice() (which returns a new array instead of modifying the original).

内容的提问来源于stack exchange，提问作者Vince Caruso