This article describes the implementation method of JavaScript to judge variable types based on custom functions. Share it for your reference, as follows:
Typeof is usually used to judge the type of js variables, but often only typeof cannot meet the requirements.
I wrote a custom function to do this, and my judgment was relatively comprehensive.
function varType(v){
if ( typeof v=== "object" ){
if (v=== null ) return 'null' ;
if (v. constructor )
return (v. constructor .toString()).match(/(?: )[/w/$]+/)[ 0 ];
if ( typeof typeof2=== 'undefined' && window .execScript){
window .execScript( 'Function vbsTypeName(o):vbsTypeName=TypeName(o):End Function' , 'vbscript' );
window .execScript( 'function typeof2(o){return vbsTypeName(o)}' , 'jscript' );
}
if ( typeof typeof2!== 'undefined' ){
return typeof2(v);
}
return "object" ;
}
return typeof v;
}
//For ordinary js constants and js objects, each browser is basically the samealert (varType()); //undefined
alert (varType( 100 )); //number
alert (varType({})); //Object
alert (varType([])); //Array
alert (varType(/ /)); //RegExp
alert (varType( new Date ())); //Date
alert (varType( Date )); //function
alert (varType( Object )); //function
alert (varType( RegExp )); //function
//For DOM objects, each browser may have different valuesalert (varType( window )); //IE:HTMLWindow2 FF:Window
alert (varType( document )); //IE:HTMLDocument FF:HTMLDocument
alert (varType( document .body)); //IE:HTMLBody FF:HTMLBodyElement
alert (varType( Option )); //IE:Object FF:function
alert (varType( Image )); //IE:Object FF:function
alert (varType( navigator )); //IE:DispHTMLNavigator FF:Navigator
//The following are only applicable to IE, and other kernel browsers do not support italert (varType( ActiveXObject )); //IE:function
alert (varType( Enumerator )); //IE:function
alert (varType( new ActiveXObject ( "" ))); //IE:Dictionary
alert (varType( new Enumerator ())); //IE:Enumerator
For more information about JavaScript, readers who are interested in reading this site's special topic:Summary of JavaScript mathematical operations usage》、《Summary of JavaScript search algorithm skills》、《Summary of JavaScript Errors and Debugging Skills》、《Summary of JavaScript data structure and algorithm techniques"and"Summary of JavaScript traversal algorithm and skills》
I hope this article will be helpful to everyone's JavaScript programming.