javascript中==,===,!=,!==的区别

javascript中比较运算符区别举例

<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8">
        <title>比较运算符</title>
    </head>
    <body>
        <script>
            var owList=null;
            if(owList!==null){
                console.log(" 不绝对等于（值和类型有一个不相等，或两个都不相等）")
            }
            if(owList!=null){
                console.log("不等于");
            }
            if(owList==null){
                console.log("值为null")
            }
        </script>
    </body>
</html>

　　效果图

<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8">
        <title>比较运算符</title>
    </head>
    <body>
        <script>
            var owList=new Array();
            if(owList!==null){
                console.log(" 不绝对等于（值和类型有一个不相等，或两个都不相等）")
            }
            if(owList!=null){
                console.log("不等于");
            }
            if(owList==null){
                console.log("值为null")
            }
        </script>
    </body>
</html>

　　效果图

<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8">
        <title>比较运算符</title>
    </head>
    <body>
        <script>
            var temp="123";
            var tempOne=123;
            var tempTwo="12";
            if(temp==tempOne){
                console.log("值想等");
            }
            if(temp===tempOne){
                console.log("类型和值都想等");
            }
            if(temp!=tempOne){
                console.log("temp和tempOne值不相等");
            }
            if(temp!=tempTwo){
                console.log("temp和tempTwo值不相等");
            }
            if(temp!==tempOne){
                console.log("不绝对等于（值和类型有一个不相等，或两个都不相等）");
            }
        </script>
    </body>
</html>