Commonly used JavaScript numerical manipulation techniques

JavaScript is a high-level programming language that can be used to implement dynamic web pages and various interactive functions. In JavaScript, we can modify numerical values ​​through some simple codes. This is very important because in actual project development, we often need to perform numerical operations.

Now, I will introduce you to some commonly used JavaScript numerical manipulation techniques.

1. Basic arithmetic operations

The most basic numerical operations in JavaScript are arithmetic operations, including addition, subtraction, multiplication and division. We can use the plus sign ( ), minus sign (-), multiplication sign (*) and division sign (/) to perform arithmetic operations, for example:

var x = 5;
var y = 3;
var z = x + y; // z的值为8
var w = x - y; // w的值为2
var u = x * y; // u的值为15
var v = x / y; // v的值为1.6666666666666667

2. Rounding of values

In JavaScript, we can use the methods provided in the Math object to perform numerical rounding operations. Commonly used methods include rounding off, rounding up, and rounding. For example:

1. The Math.floor() method is rounding down, which will round a value down to the nearest integer:

var a = Math.floor(2.75); // a的值为2

2. Math.ceil() method is rounding up, it will round a value up to the nearest integer:

var b = Math.ceil(2.25); // b的值为3

3. Math.round() method is rounding, it will Round a value to the nearest integer:

var c = Math.round(2.5); // c的值为3
var d = Math.round(2.49); // d的值为2

3. Numeric formatting

In actual project development, we often need to format values ​​into a specific format . In JavaScript, we can use the toPrecision() method and the toFixed() method to perform numerical formatting operations.

1. The toPrecision() method can format a value to a specific precision, and the return result is a string type:

var x = 1234.56789;
var y = x.toPrecision(6); // y的值为"1234.57"

2. The toFixed() method can A numerical value is formatted to a specific number of decimal places, and the returned result is a string type:

var x = 1234.56789;
var y = x.toFixed(2); // y的值为"1234.57"

4. Random number generation

In JavaScript, we can use the Math object provided method to generate random numbers. Commonly used methods include Math.random() method and Math.floor() method.

1. Math.random() method can generate random numbers between 0 and 1, excluding 1 itself:

var x = Math.random(); // x的值为0到0.99999之间的一个随机数

2. In order to generate greater randomness Number, we can use the Math.random() method with the Math.floor() method:

var x = Math.floor(Math.random() * 100); // x的值为0到99之间的一个随机整数

5. Numerical judgment

In JavaScript, we can use isNaN( ) method to determine whether a value is NaN (Not-a-Number). For example:

var x = "hello";
var y = isNaN(x); // y的值为true，因为"hello"不是一个数字

At the same time, JavaScript also provides the isFinite() method to determine whether a value is a finite value. For example:

var x = 123;
var y = isFinite(x); // y的值为true，因为123是一个有限数值

Summary

There are many numerical operations in JavaScript. We have learned basic arithmetic operations, numerical rounding, numerical formatting, random number generation and numerical judgment. These operations It can help us perform numerical processing more conveniently in actual project development.

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