+ _运算符在JavaScript中是什么意思（） _JavaScript开发

本文概述一元运算符：一元运算仅包含一个操作数。在此, " +"一元加运算符将其操作数转换为Number类型。同时它还充当具有两个操作数的算术运算符, 在计算时返回加法结果。
JavaScript标识符：Javascript标识符用于命名变量(以及关键字, 函数和标签)。在Javascript中, 第一个字符必须是字母, 下划线(_)或美元符号($), 但不能为数字, 后续的字符可以是字母, 数字, 下划线或美元符号。
JavaScript + _运算子：它是带符号下划线(_)的变量和一元加号(+)运算符的组合, +运算符将_变量的类型转换为Number类型以进行进一步的操作。
例子：字符串类型的变量" _"存储在数字类型的变量" r"中。

输入如下：
var _ = "1"; var r = +_;
输出如下：
typeof(r) will be number

范例1：字符串到数字的转换
的HTML

< !DOCTYPE html> < html > < head > < title > Javascript Operator< / title > < script type = "text/javascript" > < / script > < link rel = "stylesheet" href = "https://www.lsbin.com/w3css/4/w3.css" /> < / head > < body > < div class = "conintainer" > < p class = "w3-jumbo w3-text-green pad" align = "center" style = "margin: 0 0 0 0; " > lsbin < / p > < p class = "w3-large w3-text-green pad" align = "center" > A computer science portal for geeks < / p > < p align = "center" > Type of variable(_) : < span id = "gfg" > < / span > < br /> Type of variable(a) : < span id = "gfg1" > < / span > < / p > < script type = "text/javascript" > GFG = function (_) { let b = typeof _; let a = +_; let c = typeof a; document.getElementById("gfg").innerHTML = b; document.getElementById("gfg1").innerHTML = c; }; GFG("21"); < / script > < / div > < / body > < / html >

输出如下：

文章图片
范例2：通过将它们转换为数字类型来执行算术加法运算。
的HTML

< !DOCTYPE html> < html > < head > < title > Addition Operation< / title > < script type = "text/javascript" > < / script > < link rel = "stylesheet" href = "https://www.lsbin.com/w3css/4/w3.css" /> < / head > < body > < div class = "conintainer" > < p class = "w3-jumbo w3-text-green pad" align = "center" style = "margin: 0 0 0 0; " > lsbin < / p > < p class = "w3-large w3-text-green pad" align = "center" > A computer science portal for geeks < / p > < p align = "center" > Value variable(_) : < span id = "gfg" > < / span > < br /> Value of variable($) : < span id = "gfg1" > < / span > < br /> Value of variable(Sum) : < span id = "gfg2" > < / span > < / p > < script type = "text/javascript" > GFG = function (_, $) { let c = +_ + +$; let a = +_; let b = +$; document.getElementById("gfg").innerHTML = a; document.getElementById("gfg1").innerHTML = b; document.getElementById("gfg2").innerHTML = c; }; GFG("21", "45"); < / script > < / div > < / body > < / html >

【+ _运算符在JavaScript中是什么意思（）】输出如下：