Details about deleting attributes and adding attributes in js

For adding and deleting attributes in js, we mostly set the element attributes. Next I will introduce some examples for you to introduce their usage.

1. js Property Operation Induction

We will encounter various operations in the front-end development process, which will involve operation attributes. Below I will tell you several common attribute operations in JS. Of course, I will not explain them using examples, it is just a brief introduction of usage.

1. Common attribute operations: obj. setAttribute (attribute name)

2. class operation: obj. className = ";

3. img src operation: imgobj. src = ";

4. input value operation: inputobj. value

5. Others

Ii. js attribute operations

1. special characters not allowed in JS

2. compatibility issues: js cannot be directly resolved through the obj. style. float attribute through IE (styleFloat) or non-IE (cssFloat ).

Iii. instance (set DIV attributes)

SetAttribute method:

The Code is as follows:

Copy code

Var a = document. createElement ("div"); // create a new DIV A. id = "div1"; // name the newly added DIV A. style. setAttribute ("zIndex", 2); // sets the sequence of DIV stacked A. style. setAttribute ("textAlign", Dalign); // alignment A. style. setAttribute ("border", "# e6e7e8 1px solid"); // border color A. style. width = divwidth; // DIV width A. style. height = Dheight; // DIV height A. setAttribute ("position", "absolute "); A. style. backgroundColor = Dbgcolor; // DIV background A. setAttribute ("z-index", "2"); // DIV stacked order A. style. top = divtop + "px"; // DIV top margin A. style. left = divleft + "px"; // left margin of the DIV A. setAttribute ("innerHTML", info10 [0]. firstChild. data + "<br>" + info11 [0]. firstChild. data ); Document. body. appendChild (a); // The End of the newly created DIV. Hide div: document. getElementById ("ah"). style. display = "none" // block appears Document. getElementById ("ah"). style. disabled = "true" Document. getElementById ("ah"). style. readOnly = "true"

Summary based on the above example

1: You can use (var attrName in obj) to traverse object attributes.

2: You can use attrName in obj to determine whether an object has a certain attribute. If this attribute is not available, undefined is returned. An object can add an attribute to an object, but it does not set a value for this attribute.

3: Determine whether a property of an object is defined in its own constructor rather than inherited. You can use the obj. hasOwnProperty (attrName) function ).

4: You can determine whether an attribute can be traversed by means of for/in. You can use obj. propertyInEnumerable (attrName), but this attribute must be obtained through non-inheritance.