Why are all array values ​​​​0 in javascript? Cause Analysis

In JavaScript, there may be many reasons why an array's values ​​are all 0. Here are some reasons why this might happen:

1. Uninitialized array

In JavaScript, if you declare an array but do not assign any value to it, then All elements of this array will automatically be initialized to 0 values. For example:

let myArray = new Array(3);
// myArray现在是一个长度为3的数组，所有元素的值都为0

If you try to access uninitialized array elements, a 0 value will always be returned.

2. Use short-circuit operators

In JavaScript, if you use the logical operator "||" or "&&" to compare two values, if the If one value is 0, the second value is returned. For example:

let myArray = [];
let value = myArray[5] || 0;
// 如果myArray[5]值不存在，则返回0

In this case, if the array element does not exist, the 0 value is used as the default value.

3. The return value of some JavaScript functions is 0

In some JavaScript functions, a value of 0 is often returned (for example: parseInt(), etc.). If these functions Passing the return value directly to the array element will cause the array element to have a value of 0.

4. Programmer Error

Sometimes, programmers may accidentally assign an array value of 0 or pass an array to some special functions or methods when writing code. , the value of the element becomes 0 due to a program error.

In short, in JavaScript, there may be many reasons for the value of an array to be all 0, and the characteristics of these reasons are slightly different from the implementation of the code. The best way is to look at the code to determine why the value of the array became 0, and debug and fix the problem in the code appropriately.

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