add eslint
calcTextareaHeight.js
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// Thanks to
// https://github.com/andreypopp/react-textarea-autosize/
// https://github.com/ElemeFE/element/blob/master/packages/input/src/calcTextareaHeight.js
let hiddenTextarea;
const HIDDEN_STYLE = `
height:0 !important;
min-height:0 !important;
max-height:none !important;
visibility:hidden !important;
overflow:hidden !important;
position:absolute !important;
z-index:-1000 !important;
top:0 !important;
right:0 !important
`;
const CONTEXT_STYLE = [
'letter-spacing',
'line-height',
'padding-top',
'padding-bottom',
'font-family',
'font-weight',
'font-size',
'text-rendering',
'text-transform',
'width',
'text-indent',
'padding-left',
'padding-right',
'border-width',
'box-sizing'
];
function calculateNodeStyling(node) {
const style = window.getComputedStyle(node);
const boxSizing = style.getPropertyValue('box-sizing');
const paddingSize = (
parseFloat(style.getPropertyValue('padding-bottom')) +
parseFloat(style.getPropertyValue('padding-top'))
);
const borderSize = (
parseFloat(style.getPropertyValue('border-bottom-width')) +
parseFloat(style.getPropertyValue('border-top-width'))
);
const contextStyle = CONTEXT_STYLE
.map(name => `${name}:${style.getPropertyValue(name)}`)
.join(';');
return {contextStyle, paddingSize, borderSize, boxSizing};
}
export default function calcTextareaHeight(targetNode, minRows = null, maxRows = null) {
if (!hiddenTextarea) {
hiddenTextarea = document.createElement('textarea');
document.body.appendChild(hiddenTextarea);
}
let {
paddingSize,
borderSize,
boxSizing,
contextStyle
} = calculateNodeStyling(targetNode);
hiddenTextarea.setAttribute('style', `${contextStyle};${HIDDEN_STYLE}`);
hiddenTextarea.value = targetNode.value || targetNode.placeholder || '';
let height = hiddenTextarea.scrollHeight;
let minHeight = -Infinity;
let maxHeight = Infinity;
if (boxSizing === 'border-box') {
height = height + borderSize;
} else if (boxSizing === 'content-box') {
height = height - paddingSize;
}
hiddenTextarea.value = '';
let singleRowHeight = hiddenTextarea.scrollHeight - paddingSize;
if (minRows !== null) {
minHeight = singleRowHeight * minRows;
if (boxSizing === 'border-box') {
minHeight = minHeight + paddingSize + borderSize;
}
height = Math.max(minHeight, height);
}
if (maxRows !== null) {
maxHeight = singleRowHeight * maxRows;
if (boxSizing === 'border-box') {
maxHeight = maxHeight + paddingSize + borderSize;
}
height = Math.min(maxHeight, height);
}
return {
height: `${height}px`,
minHeight: `${minHeight}px`,
maxHeight: `${maxHeight}px`
};
}