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1.for in The for in loop is the most basic way to traverse an object, and it also gets the properties on the object’s prototype chain // Create an object and specify its prototype, bar is a property on the prototype const obj = Object . create ( { bar : ‘bar’ } ) //

Method 1: indexOf() (recommended) var str = “123”; console.log(str.indexOf(“3”) != -1 ); // true The indexOf() method returns the first occurrence of a specified string value in a string. If the string value to be retrieved does not appear, the method returns -1. Method 2: search() var str = “123”; console.log(str.search(“3”) != -1 ); //

select last_name , job_id from employees where manager_id is null ; select last_name , job_id from employees where manager_id <=> Null ; select last_name , job_id from employees where manager_id = Null ; last = null is wrong If one of the values, strings, or expressions on either side of the equal sign is NULL,

The first <script type=”text/html” id=”see-bar”> <a class=”layui-btn layui-btn-primary layui-btn-xs ” data-id=”” onclick=”see(this)” lay-event=”See” style=”color:#2880cb”>< /a> </script> table.render({ . . . , cols: [[ , { ‘13%’, title: ‘card number’, align: ‘center’, rowspan: ‘1’, toolbar: ‘#see-bar’ } ]] . . . }); the second , cols: [[ { type: … The post rendering html objects in

js method to split string Applicable to each scene is different const arr = [ ‘1-2’ , ‘1-3’ , ‘2-3’ , ‘3-4’ ] ; 1. string.split() Separated by special characters ‘1-2’ . split ( ‘-‘ ) // [‘1’, ‘2’] 2. String.substring(start,stop) start is required. A non-negative integer specifying the position in string of the first