How to set the cursor position of input with Uniapp

With the development of mobile Internet, front-end development technology is also constantly developing and innovating. As an emerging technology for front-end development, Uniapp has certain advantages in both basic syntax and practical applications. In the process of using Uniapp, we often need to set the input cursor position. This article will discuss how to use Uniapp to set the input cursor position.

1. Basic use of input
In Uniapp, we usually use the input component to obtain user input. After introducing the input component on the page, we can use the v-model directive to bind the input value. Here is a simple example:

<template>
  <div>
    <input v-model="inputValue" />
    <button @click="submit">提交</button>
  </div>
</template>

<script>
  export default {
    data() {
      return {
        inputValue: ""
      };
    },
    methods: {
      submit() {
        console.log(this.inputValue);
      }
    }
  };
</script>

In the above example, we defined an input component and a button. The input value is bound to the inputValue variable through the v-model instruction, and then the input value is obtained and processed through the submit method.

2. Set the input cursor position
In actual development, we often need to set the cursor position in the input box, such as moving the cursor to the end of the input box after clicking a button, or in During initialization, the cursor is set to a certain position in the input box by default, etc. The following are some commonly used methods to set the cursor position:

1. Use the focus method of Element

Element is a commonly used UI component library in Uniapp, and the input component is also in Element defined in. You can get an instance of the input component by calling the $refs property of input, and then use the focus method of Element to set the cursor position. Here is an example:

<template>
  <div>
    <input ref="input" v-model="inputValue" />
    <button @click="moveCursorToEnd">移动光标到末尾</button>
  </div>
</template>

<script>
  export default {
    data() {
      return {
        inputValue: ""
      };
    },
    methods: {
      moveCursorToEnd() {
        this.$refs.input.focus();
        let len = this.inputValue.length;
        this.$refs.input.setSelectionRange(len, len);
        // 或者使用以下语句，将光标设置在最后一个字符之后
        // this.$refs.input.setSelectionRange(len+1, len+1);
      }
    }
  };
</script>

In the above example, we assign it to an instance of input by adding a ref attribute to the input, and then use the this.$refs.input.focus() method in the moveCursorToEnd method. Move the cursor into the input box, and then set the cursor position through the this.$refs.input.setSelectionRange() method.

2. Use the setRange method of Selection

Selection is an API provided natively by the browser to operate the selection, and it can also be used in Uniapp. We can set the cursor position by getting the selection object and then using the setRange method. The following is an example:

<template>
  <div>
    <input ref="input" v-model="inputValue" />
    <button @click="moveCursorToPosition">移动光标到第3个字符后面</button>
  </div>
</template>

<script>
  export default {
    data() {
      return {
        inputValue: ""
      };
    },
    methods: {
      moveCursorToPosition() {
        let target = this.$refs.input;
        let range = document.createRange();
        range.selectNodeContents(target);
        range.setStart(target.childNodes[0], 2);
        range.setEnd(target.childNodes[0], 2);
        let sel = window.getSelection();
        sel.removeAllRanges();
        sel.addRange(range);
      }
    }
  };
</script>

In the above example, we first use the document.createRange() method to create a selection object range, and then set its range to all nodes of the input, and then use range.setStart and The range.setEnd method sets the range of the selection object to the third character. Finally, use the window.getSelection() method to obtain the selection object, use the sel.removeAllRanges() method to clear the selection object, and then use the sel.addRange() method to add the range object to the selection object. This successfully sets the cursor position.

3. Summary
The above are some common methods for setting the cursor position of input using Uniapp. Readers can choose according to actual needs. During use, if you have any other questions, you are welcome to communicate and discuss.

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