clear()
Map对象的功能从当前Map对象中删除所有元素。
其语法如下
mapVar.clear()
<html> <head> <title>JavaScript Example</title> </head> <body> <script type="text/javascript"> var mapVar = new Map(); mapVar.set('1', 'Java'); mapVar.set('2', 'JavaFX'); mapVar.set('3', 'HBase'); mapVar.set('4', 'Neo4j'); var map = mapVar.clear(); document.write("Size of the map object: "+mapVar.size); </script> </body> </html>
输出结果
Size of the map object: 0
<html> <head> <title>JavaScript Example</title> </head> <body> <script type="text/javascript"> var mapVar = new Map(); mapVar.set('1', 'Raju'); mapVar.set('2', 'Ram'); mapVar.set('3', 'Rahim'); mapVar.set('4', 'Robert'); document.write("Size of the map: "+mapVar.size); var map = mapVar.clear(); document.write("<br>"); document.write("Size of the map after clearing its contents using clear() function: "+mapVar.size); </script> </body> </html>
输出结果
Size of the map: 4 Size of the map after clearing its contents using clear() function: 0