JavaScript基本语法指南（注释用法实例） _YAML语法

注释用于防止执行语句。编译器执行代码时, 注释将被忽略。注释是用户友好的, 因为用户可以使用注释获得代码的解释。
语法如下：

// For single line comment

/* For block of lines comment......*/

返回值：在执行代码期间, 注释将被忽略。
范例1：此示例说明了使用//的单行注释。

< !DOCTYPE html> < html > < head > < title > JavaScript Comments < / title > < script > // Function to add two numbers function add() {// Declare three variables var x, y, z; // Input a number and store it into variable x x = Number( document.getElementById("num1").value ); // Input a number and store it into variable x y = Number( document.getElementById("num2").value ); // Sum of two numbers z= x +y; // Return the sum document.getElementById("sum").value = https://www.lsbin.com/z; } < / script > < / head > < body > Enter the First number: < input id ="num1" > < br > < br > Enter the Second number: < input id = "num2" > < br > < br > < button onclick = "add()" > Sum < / button > < input id = "sum" > < / body > < / html >

输出如下：
在单击按钮之前：

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【JavaScript基本语法指南（注释用法实例）】单击按钮后：

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范例2：此示例说明了使用/ *…* /的多行注释

< !DOCTYPE html> < html > < head > < title > JavaScript Comments < / title > < script > /* Script to get two input from user and add them */ function add() {/* Declare three variable */ var x, y, z; /* Input the two nos. num1, num2 Input num1 and store it in x Input num2 and store it in y The sum is stored in a variable z*/ x = Number(document.getElementById("num1").value); y = Number(document.getElementById("num2").value); z = x + y; document.getElementById("sum").value = https://www.lsbin.com/z; } < / script > < / head > < body > Enter the First number : < input id ="num1" > < br > < br > Enter the Second number: < input id = "num2" > < br > < br > < button onclick = "add()" > Sum < / button > < input id = "sum" > < / body > < / html >

输出如下：
在单击按钮之前：

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单击按钮后：

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范例3：此示例说明注释的代码将永远不会执行。

< !DOCTYPE html> < html > < head > < title > JavaScript Comments < / title > < script > function add() {var x, y, z; x = Number( document.getElementById("num1").value ); y = Number( document.getElementById("num2").value ); z= x +y; // Comment the code section //document.getElementById("sum").value = https://www.lsbin.com/z; } < / script > < / head > < body > Enter the First number: < input id ="num1" > < br > < br > Enter the Second number: < input id = "num2" > < br > < br > < button onclick = "add()" > Sum < / button > < input id = "sum" > < / body > < / html >

输出如下：
在单击按钮之前：