JavaScript比较运算符用法和介绍指南

2021年4月6日19:35:24 发表评论 702 次浏览

下面是比较运算符的示例。

范例1:

<script> 
     function gfg() { 
     let val1 = 5; 
     // Equality Operators
     document.write(val1 == 5);
     document.write( "<br>" );
     // Relational Operators
     document.write(val1 > 0);
     } 
     gfg(); 
</script>

输出如下:

true
true

操作符用于对操作数执行特定的数学和逻辑计算。像C, C ++, Java, Python和其他各种语言一样, JavaScript也支持比较方式操作。比较运算符在逻辑语句中用于确定变量或值之间的相等性或差异。 JavaScript支持各种比较运算符:

  • 平等经营者
  • 关系运算符

平等经营者

平等(==):该运算符用于比较两个操作数的相等性。如果相等, 则条件为true, 否则为false。

语法如下:

x == y

以下示例说明了(==)JavaScript中的运算符:

范例1:

<script>
     // Illustration of (==) operator
     let val1 = 5;
     let val2 = '5' ;
  
     // Checking of operands
     console.log(val1 == 5);
     console.log(val2 == 5);        
     console.log(val1 == val1);
  
     // Check against null and boolean value
     console.log(0 == false );   
     console.log(0 == null );
</script>

输出如下:

> true
> true
> true
> true
> false

范例2:

<script>
     // Illustration of (==) operator
     let obj1 = { 'val1' : 'value' };
     let obj2 = { 'val2' : 'value' };
  
     // Checking of operands
     console.log(obj1.val1 == 'value' );        
     console.log(obj1 == obj2);
     console.log(obj1.val1 == obj2.val2);
  
     // Check against undefined
     console.log(0 == undefined);   
     console.log( null == undefined);
</script>

输出如下:

> true
> false
> true
> false
> true

一世平等(!=):该运算符用于应对两个操作数的不等式。如果相等, 则条件为假, 否则为真。

语法如下:

x != y

以下示例说明了(!=)操作符inJavaScript:

范例1:

<script>
     // Illustration of (!=) operator
     let val1 = 5;
     let val2 = '5' ;
  
     // Checking of operands
     console.log(val1 != 6);
     console.log(val2 != '5' );        
     console.log(val1 != val1);
  
     // Check against null and boolean value
     console.log(0 != false );   
     console.log(0 != null );
</script>

输出如下:

> true
> false
> false
> false
> true

范例2:

<script>
     // Illustration of (!=) operator
     let obj1 = { 'val1' : 'value' };
     let obj2 = { 'val2' : 'value' };
  
     // Checking of operands
     console.log(obj1.val1 != 'value' );        
     console.log(obj1 != obj2);
     console.log(obj1.val1 != obj2.val2);
  
     // Check against undefined
     console.log(0 != undefined);   
     console.log( null != undefined);
</script>

输出如下:

> false
> true
> false
> true
> false

严格平等(===):该运算符用于要求两个操作数的类型相等。如果值和类型都相等, 则条件为true, 否则为false。

语法如下:

x === y

以下示例说明了(===)操作符inJavaScript:

范例1:

<script>
     // Illustration of (===) operator
     let val1 = 5;
     let val2 = '5' ;
  
     // Checking of operands
     console.log(val1 === 6);
     console.log(val2 === '5' );        
     console.log(val1 === val1);
  
     // Check against null and boolean value
     console.log(0 === false );   
     console.log(0 === null );
</script>

输出如下:

> false
> true
> true
> false
> false

范例2:

<script>
     // Illustration of (===) operator
     let obj1 = { 'val1' : 'value' };
     let obj2 = { 'val2' : 'value' };
  
     // Checking of operands
     console.log(obj1.val1 === 'value' );        
     console.log(obj1 === obj2);
     console.log(obj1.val1 === obj2.val2);
  
     // Check against undefined
     console.log(0 === undefined);   
     console.log( null === undefined);
</script>

输出如下:

> true
> false
> true
> false
> false

严格的平等(!==):该运算符用于ompare两个具有类型的操作数的不等式。如果值和类型都不相等, 则条件为true, 否则为false。

语法如下:

x !== y

以下示例说明了(!==)操作符inJavaScript:

范例1:

<script>
  // Illustration of (!==) operator
  let val1 = 5;
  let val2 = '5' ;
  
  // Checking of operands
  console.log(val1 !== 6);
  console.log(val2 !== '5' );        
  console.log(val1 !== val1);
  
  // Check against null and boolean value
  console.log(0 !== false );   
  console.log(0 !== null );
</script>

输出如下:

> true
> false
> false
> true
> true

范例2:

<script>
     // Illustration of (!==) operator
     let obj1 = { 'val1' : 'value' };
     let obj2 = { 'val2' : 'value' };
  
     // Checking of operands
     console.log(obj1.val1 !== 'value' );        
     console.log(obj1 !== obj2);
     console.log(obj1.val1 !== obj2.val2);
  
     // Check against undefined
     console.log(0 !== undefined);   
     console.log( null !== undefined);
</script>

输出如下:

> false
> true
> false
> true
> true

关系运算符

G胜于运算符(>):这个运算符习惯于检查左侧值是否大于右侧值。如果值较大, 则条件为true, 否则为false。

语法如下:

x > y

以下示例说明了(>)操作符inJavaScript:

范例1:

<script>
     // Illustration of (>) operator
     let val1 = 5;
     let val2 = "5" ;
  
     // Checking of operands
     console.log(val1 > 0);
     console.log(val2 > "10" );        
     console.log(val1 > "10" );
     console.log(val2 > 0);
</script>

输出如下:

> true
> true
> false
> true

范例2:

<script>    
     // Illustration of (>) operator
     let obj1 = { 'val1' : 1};
     let obj2 = { 'val2' : 3};
  
     // Checking of operands
     console.log(obj1.val1 > 0);        
     console.log(obj1 > obj2);
     console.log(obj1.val1 > obj2.val2);
     console.log(obj2 > obj1);
     console.log(obj2.val2 > obj1.val1);
</script>

输出如下:

> true
> false
> false
> false
> true

G大于或等于运算符(> =):这个运算符习惯于检查左侧操作数是否大于或等于右侧操作数。如果值是g大于或等于那么条件为真, 否则为假。

语法如下:

x >= y

以下示例说明了(> =)操作符inJavaScript:

范例1:

<script>
  // Illustration of (>=) operator
  let val1 = 5;
  let val2 = "5" ;
  
  // Checking of operands
  console.log(val1 >= 5);
  console.log(val2 >= "15" );        
  console.log(val1 >= "5" );
  console.log(val2 >= 15);
</script>

输出如下:

> true
> true
> true
> false

范例2:

<script>
     // Illustration of (>=) operator
     let obj1 = { 'val1' : 1};
     let obj2 = { 'val2' : 3};
  
     // Checking of operands
     console.log(obj1.val1 >= 0);        
     console.log(obj1 >= obj2);
     console.log(obj1.val1 >= obj2.val2);
     console.log(obj2 >= obj1);
     console.log(obj2.val2 >= obj1.val1);
</script>

输出如下:

> true
> true
> false
> true
> true

大号比操作员重要(<):这个运算符习惯于检查左侧值是否小于右侧值。如果是, 则条件为真, 否则为假。

语法如下:

x < y

以下示例说明了(<)操作符inJavaScript:

范例1:

<script>
  // Illustration of (<) operator
  let val1 = 5;
  let val2 = "5" ;
  
  // Checking of operands
  console.log(val1 < 15);
  console.log(val2 < "0" );        
  console.log(val1 < "0" );
  console.log(val2 < 15);
</script>

输出如下:

> true
> false
> false
> true

范例2:

<script>
     // Illustration of (<) operator
     let obj1 = { 'val1' : 1};
     let obj2 = { 'val2' : 3};
  
     // Checking of operands
     console.log(obj1.val1 < 10);        
     console.log(obj1 < obj2);
     console.log(obj1.val1 < obj2.val2);
     console.log(obj2 < obj1);
     console.log(obj2.val2 < obj1.val1);
</script>

输出如下:

> true
> false
> true
> false
> false

大号等于或小于等于运算符(<=):该运算符用于检查左侧操作数的值是否小于或等于右侧操作数的值。如果是, 则条件为真, 否则为假。

语法如下:

x <= y

以下示例说明了(<=)操作符inJavaScript:

范例1:

<script>
     // Illustration of (<=) operator
     let val1 = 5;
     let val2 = "5" ;
  
     // Checking of operands
     console.log(val1 <= 15);
     console.log(val2 <= "0" );        
     console.log(val1 <= "0" );
     console.log(val2 <= 15);
</script>

输出如下:

> true
> false
> false
> true

范例2:

<script>
     // Illustration of (<=) operator
     let obj1 = { 'val1' : 1};
     let obj2 = { 'val2' : 3};
  
     // Checking of operands
     console.log(obj1.val1 <= 10);        
     console.log(obj1 <= obj2);
     console.log(obj1.val1 <= obj2.val2);
     console.log(obj2 <= obj1);
     console.log(obj2.val2 <= obj1.val1);
</script>

输出如下:

> true
> true
> true
> true
> false

支持的浏览器:所有人都支持的浏览器JavaScript比较运算符下面列出:

  • 谷歌浏览器
  • 火狐浏览器
  • 歌剧
  • 苹果浏览器
  • Edge
  • IE浏览器

木子山

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