Some common public js methods used in uniapp

With the continuous development of front-end development, more and more developers choose to use uniapp to develop cross-platform applications. uniapp is a development platform based on the Vue.js framework, which can quickly create applications that need to run on multiple platforms at the same time. In this case, using public js methods is an effective way to achieve code reuse and improve development efficiency. This article will introduce some common public js methods used in uniapp.

1. Obtain page parameters

In uniapp, we can easily obtain the parameters of the current page through the uni.getStorageSync(key) method. For example, if we want to get the page ID, we can do it through the following code:

const query = this.$mp.page.options;
const id = query.id;

Here this.$mp.page.options represents the collection of current page parameters, where query.id is the id value in the parameter. Through this This way we can easily get the value of any parameter in the page.

2. Methods to prevent jitter

In some pages with complex functions, many operations will trigger events. If the user clicks frequently, it will cause data instability. At this time, we can use the method of preventing jitter to solve this problem. Anti-shake means that multiple calls to the same function are executed only once within a period of time. Usually we use a timer to achieve this. As shown below:

var timer=null;
function debounce(fn,time){
    if(timer!=null){
        clearTimeout(timer)
    }

    timer=setTimeout(function(){
        fn()
    },time)
}

调用：

debounce(function(){
    console.log('防抖成功')
},1000)

In the above code, the function of the debounce method is to prevent this function from being executed multiple times in a short period of time. time is the set time window value. When the function is called, no matter how long it is called within wait milliseconds No matter how many times, the function will only be executed once.

3. Obtain the corresponding value in the object based on the key value

In some scenarios where complex data structures need to be processed, we usually encounter the need to obtain the corresponding value in the object based on the key value. Value needs. For example, the following array:

let arr = [
    { name: '张三', age: 18 },
    { name: '李四', age: 19 },
    { name: '王五', age: 20 }
]

If you want to get the age value of the object named Li Si, you can use the following code to achieve it:

function findValue(arr, key, value) {
    for (let i = 0; i < arr.length; i++) {
        if (arr[i][key] == value) {
            return arr[i]
        }
    }
    return null
}

var result = findValue(arr,'name','李四')
console.log(result.age) // 19

In the above code, the function of the findValue method is in the array Find an object that meets the criteria and return this object. Where arr is an array, key is the attribute name within the array element, and value is the attribute value to be found.

4. Determine the variable type

In some data processing scenarios, we need to determine the type of the variable to proceed with the next step. The typeof method in JavaScript can easily obtain the type of a variable:

console.log(typeof 'uniapp') // string
console.log(typeof true) // boolean
console.log(typeof 1) // number
console.log(typeof undefined) // undefined
console.log(typeof null) // object
console.log(typeof {}) // object
console.log(typeof []) // object
console.log(typeof function() {}) // function

It should be noted that the result of typeof null is 'object', which is a historical problem of JavaScript.

To sum up, the above four public js methods are often used in uniapp development, which can greatly improve development efficiency. Hope this article can be helpful to you.

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