Input text box in HTML, initial text hint, when clicked, the text disappears

JS Solution
Use the onfocus event to check the current value and, if it is the default value, empty the Value property. For example:
<input type= "text" value= "Please enter the content" onfocus= "javascript:if (this.value== ' please input content ') this.value= ';" >
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The implementation method of the placeholder property of HTML5
<input type= "text" value= "Please enter text" onfocus= "this.value=" "onblur=" if (this.value== ") {this.value= ' Please enter text '}"/>

Input text box in HTML, initial text hint, when clicked, the text disappears