jquery data type conversion

jQuery is a very excellent JavaScript library that can easily manipulate and process HTML documents, handle events, dynamically change CSS and page content, and even perform Ajax operations. During the development process of jQuery, we often encounter the conversion of various data types. This article will introduce in detail the commonly used data type conversion methods in jQuery.

1. Number conversion

1. parseInt method

The parseInt method can convert the string type to the integer type, and can also specify the forward format:

var num = parseInt("123");
console.log(num); // 123

var num = parseInt("123.67");
console.log(num); // 123

var num = parseInt("0xfad", 16);
console.log(num); // 4013

2. parseFloat method

The parseFloat method can convert the string type to a floating point number type, and can also truncate or retain the specified number of digits:

var float = parseFloat("123.67");
console.log(float); // 123.67

var float = parseFloat("123.671284");
console.log(float.toFixed(2)); // 123.67

2. String conversion

1. toString method

The toString method can convert the numerical type to the string type, and can also specify the carry system:

var num = 123;
console.log(num.toString()); // "123"

var num = 10;
console.log(num.toString(2)); // "1010"

2. join method

join method can convert the array type to string type:

var array = [1, 2, 3, 4];
console.log(array.join()); // "1,2,3,4"
console.log(array.join("-")); // "1-2-3-4"

3. Array conversion

1. toArray method

toArray method can convert array-like objects into real array objects:

var args = function() { 
    return arguments; 
}(); // 注意这里必须要加括号，否则会被当成语句块处理

var arr = Array.prototype.slice.call(args);
console.log(arr); // [1, 2, "hello"]

2. from method

from method can convert certain array-like objects into Convert the object to a real array object:

var set = new Set([1, 2, 3]);
var arr = Array.from(set);
console.log(arr); // [1,2,3]

4. Object conversion

1. JSON.stringify method

The JSON.stringify method can convert any object Into JSON string:

var obj = {
    name: "Tom",
    age: 20
};

console.log(JSON.stringify(obj)); // {"name":"Tom","age":20}

2. $.param method

$.param method can convert any object into a serialized string:

var obj = { name: "Tom", age: 20 };

console.log($.param(obj)); // "name=Tom&age=20"

5. Others

1. typeof method

typeof method can determine the data type:

console.log(typeof 123); // "number"
console.log(typeof "123"); // "string"
console.log(typeof true); // "boolean"
console.log(typeof null); // "object"
console.log(typeof undefined); // "undefined"
console.log(typeof {}); // "object"
console.log(typeof []); // "object"
console.log(typeof function() {}); // "function"

2. isNumeric method

isNumeric method can determine whether a value is a number:

console.log($.isNumeric("123")); // true
console.log($.isNumeric(123)); // true
console.log($.isNumeric("1e5")); // true
console.log($.isNumeric("1.23")); // true
console.log($.isNumeric("0xF")); // true
console.log($.isNumeric("hello")); // false

During the development process, we need to frequently convert data types. The methods mentioned above are all must be understood for development. Hope it helps everyone.

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